Hello Peter- In some ways I'm involved with Re buying and selling as well as an investment vehicle, and I deal with the Maine RE Investment Assoc. as well.
While it may not be public record what the seller's true bottom line is, it is public record what the owner's mortgage balance was- and with some quick math it's pretty likely you can figure out what they still owe on it today as its on the market. Whenever I look at a property on paper to see if it could be had for a low number, I check out this angle.
You need to find out what their payoff amount is at the house closing. That's just one way to pass on one investment property and look at the next option. Thanks, and good luck,