Sellers who receive offers to buy their homes from a third party who will fix the place up a bit and resell it are always left with a nagging question: Could I have gotten more?

Now there's a new tool to help sellers answer those questions. It's called the "Offer Optimizer," and it will help you make a side-by-side comparison of offers made online or in person. That's the only way sellers can make a sound monetary decision on how to proceed.

The "I" in the term I-Buyer stands for several things. The internet, for one, because most of these outfits work almost exclusively on the web. Instant, for another, because they promise to make you an offer within just a few days and, if you accept, to close quickly, paying you in cash.

This kind of service is nothing new. Many realty firms and agents offer what are known as "buy-in" programs that will be happy to take your property off your hands. Then there the so-called bottom-feeders like HomeVesters of "We Buy Ugly Houses" fame and House Buyers of America.

None of these buyers will pay sellers top dollar. After all, they have to make something for their troubles. Worse, the discount sometimes can be steep, as much as 50 percent less than what you might sell for on the open market if the house is in good shape and in a solid market.

Lately, though, there has been a movement to institutionalize buy-in programs so the rules are the same nationally for everyone. And everyone, it seems, is getting in on the act. So far, the leading I-Buyers are Offerpad and Opendoor, but Zillow is ramping up quickly, as is Redfin Now and several others.

Offerpad and Opendoor, the two largest players so far, work very much the same way. Take five minutes to complete Offerpad's online form -- include pictures, if you like -- and you'll receive an offer within 24 hours or so. It uses automated valuation algorithms and artificial intelligence to determine its offers, which it says are "competitive."

Similarly, tell Opendoor about your home's details and receive an offer within a few clicks. Add unique details for a more precise offer. If you accept, the company will send out an inspector to confirm what you said. And if everything checks out, you can close within a few days.

Both companies say what they pay -- in cash -- is fair, depending on the home's condition and the state of the local market. And both charge service fees "similar to what a traditional real estate agent would charge." The fee averages 6 percent with both companies. But it can be lower or higher -- lower if the house is pristine and in a hot market, and higher if it requires lots of work.

I-Buyers, sometimes known as "disruptors" because of how they hope to reshape the market, command only a small portion of the business now. One source says homes sold via instant offers accounted for a minuscule 0.2 percent of all existing home sales last year.

But they are expected to grow exponentially. In Phoenix, where several I-Buyers compete for business, they bought in 5 percent of all resale houses -- one in 20 -- in 2018. Meanwhile, Zillow has made its buy-in program a high priority. And Opendoor expects to be up and running in 50 major markets by next year.

Realize, though, that all offers are not the same. Which again begs the question: How do you know you're being offered as much as you can get?

Enter Offer Optimizer, which will make three comparisons: one from a national I-Buyer, one from a local I-Buyer and one related to what you can expect to obtain by using a local agent to sell the traditional way. If more than one I-Buyer is active in your market, the tool will obtain offers from all that are available.

The online tool will provide a detailed breakdown of each offer's fees and costs as well as the typical time frame for a sale to be completed.

At this time, the Optimizer is operational in 21 major markets where I-buying is taking hold. It's a free service from zavvie, a matching service that connects buyers and sellers to agents who specialize in their local markets and never travel far afield to score a listing or a sale.

"Time is money. The question for most sellers is: How much money?" says zavvie's Lane Hornung. The program (zavvie.com/offer-optimizer) "puts instant offers on overdrive, ensuring sellers squeeze every last dollar out of their home sale."

When it comes to new home communities, bigger is often better, to builders as well as buyers.

Master planned communities, or MPCs, are defined as properties for which every element and consideration is planned from the get-go and the community is contracted to follow that plan exactly.

“Developers have learned that they can achieve even more sales and higher prices by joining forces with adjacent land owners to create larger master planned communities with scale,” John Burns Real Estate Consulting, based in Irvine, California, said in a recent report. The company calls these “mega masterplans.”

John Burns Real Estate Consulting figures some 28,000 people bought new homes in the top 50 MPCs last year. That’s nearly 5 percent of the estimated 613,000 new houses sold in 2018. The company also reports that each of the top 50 sold at least 320 new units last year, or nearly one a day.

The problem with MPCs is that houses within their borders usually come at premium prices. After all, someone has to pay for all that good stuff. So, if you are extremely cost-conscious, you might want to stick with stand-alone communities. “There are plenty of nicely done free-standing communities,” says Jody Kahn, a senior vice president at the Burns consulting outfit.

If you are after the perks, though, there are perhaps 500 or so MPCs throughout the country to choose from. Here are some things to consider:

-- Amenities: If you can’t find a house you like, then this is a moot point. But once you do, take a hard look at the amenities package. There’s no rule of thumb about what has to be offered, but Kahn says that “at a minimum,” the place should feature “a solid water-themed amenity,” a pool and clubhouse, perhaps a lagoon or lake. “People really gravitate to water.”

Twenty years ago, a golf course or two was a must-have feature, but no more. Lately, interests have shifted toward things like walking and biking trails that are not paved to give the property a less-developed appearance. Estrella in Goodyear, Arizona, outside Phoenix, will include more than 50 miles of paths and trails for residents’ use.

Parks in and between neighborhoods are popular these days, too, as are social networks and a healthy lifestyle. Harvest in Argyle, Texas, near Dallas, has a working farm with community and private plots.

“Our research -- and my own personal experience -- shows that we boomers value organic, unplanned, authentic, and experience-based housing amenities the most,” says Kate Seabaugh, a Burns research manager. “What should also interest the boomers is that these amenities are generally not expensive.”

-- Housing: A well-designed and successful MPC will offer a wide range of houses, sizes and prices to draw a variety of owners, from millennials to seniors. Look for small, medium and large lot offerings, as well as a broad offering of housing types, both single and multi-family.

-- Competition: There’s no rule of thumb, either, on the ideal number of builders active in the MPC, but there shouldn’t be so many that they cannibalize each other. A certain amount of overlap won’t hurt, says Kahn. But if every builder is marketing to the same buyer, some are going to fail.

-- Financials: Check your builder’s financials to make sure they have the wherewithal to weather a downturn in sales and will be around to live up to their warranty, whether one year or longer. Also check on the stability of the developer so you can be as certain as possible that all that has been promised will be delivered.

During the 2006-2008 housing recession, one of the four builders who joined together to develop Inspirada in Las Vegas slipped into bankruptcy, putting extra pressure on the other three to carry on. Luckily, they managed to pick up the slack, and the property is now flourishing.

-- The Rules: The regulations with which you will have to live by are there to maintain the common areas and housing values. They help create a “nice little wonderland,” says Kahn. But in an MPC, there might be rules for your neighborhood as well as another set of requirements for the overall community, so you have to be doubly attentive. Otherwise, you might run afoul of the law. For example: You may not be able to park your boat, RV or working vehicle at your own house.

There comes a time in every real estate investor’s life when he has to decide whether to operate his rental business by himself or turn the day-to-day workings over to a professional property manager.

If you decide you need help, the next question is: How do you choose a property manager? Yes, they can be expensive. The going rate is 10-15 percent of the monthly rent, with the fee in some vacation home markets running as high as 40 percent. But the right one can be worth his or her weight in gold.

Managers come in all shapes and sizes, from single individuals -- usually real estate agents -- who specialize in rentals to big companies to property management chains a la McDonalds and Subway. The services they provide will depend on your specific needs.

Typically, though, they deal directly with tenants so you don’t have to. Remember, a passive investment isn’t passive if you have to work at it. So a good property manager will separate the operation side from the investment side, says Gary Beasley of Roofstock, an online marketplace where buyers and sellers trade in single-family rental properties.

A good property manager will help you determine how much rent to charge, take applications from would-be renters, run credit reports on them, check their references, speak with their current and former landlords, and make sure they work where they say they do and make what they say they make. Some even use screening companies to make sure possible tenants are on the up-and-up and have not been evicted from other properties.

Among other things, Reiss Properties in Las Vegas uses a detailed lease written for the company by a real estate lawyer, collects a security deposit and the first month’s rent in full before allowing anyone to move in, and it requires tenants to have renters insurance to protect their personal property.

It also uses a 12-page walkthrough report, completed before a tenant moves in and after he or she moves out, takes hundreds of digital pictures to document damage, and makes regular visits to the property. It even makes clients’ mortgage payments if they desire.

To find a property manager that’s right for you, start by contacting your local association of apartment owners for a list of manager-members. Look for affiliates of the Institute of Real Estate Management and the National Association of Residential Property Managers, or ask for referrals from friends and associates who also own rental properties.

Performing this kind of due diligence is key, advises Doug Brien, co-founder of MYND Property Management, which oversees 3,500 units on the West Coast. It’s “just as important” as doing your homework when selecting properties themselves, he says.

Of course, you’ll want to make sure the managers you are considering are bonded and licensed. Just because someone is a licensed real estate agent doesn’t necessarily mean that he or she can act as a property manager. In many jurisdictions, a separate license is required.

Once you settle on two or three potential managers, check their references. Speak with several clients to get a feel for how the candidates operate. You’ll specifically want to know about whatever shortcomings the managers have, such as charging you their monthly fee whether the tenant pays his rent or not. After all, if they can’t collect, why should you have to pay?

Brien of MYND says to be leery of online reviews, which he warns are “highly subjective and polarizing,” and therefore should be taken with a grain of salt. For one thing, some tenants post complaints as a tool to negotiate a better deal with their landlords, he explains. For another, some sites may not display reviews posted by people who are not otherwise active on their sites.

Another aspect of the manager’s job that you’ll want to consider is how he or she reports to you. For example, do they have an online portal you can access to look at bills, rent payments and so on? In addition, your tenant should be able to report maintenance issues and pay their rent electronically.

At the minimum, according to Roofstock, you should be given photos of any damage and written estimates for repairs. Once you give the OK and the repairs are made, you should receive an itemized statement of the costs.

How your rent is collected will determine how quickly your share is forwarded to you. If it is done electronically, it can be deposited directly into your bank account almost as soon as the manager receives it. But if it is all done by check and by mail, it could be weeks before you get your money.

Read the manager’s contract with a specific eye toward how you can cancel the manager’s services if you don’t like how he is performing. Some allow you to opt out with a 30-day notice, but others require you to remain a client for up to 90 days after you give notice you want to dissolve the relationship.

Other contract provisions to study include whether you will have to pay extra for such things as legal representation, evictions and the like, how late fees are charged and who gets them (you or the manager), and how your place will be marketed to new tenants when the old ones leave.