Space just has a such a mysterious appeal - the vast unknown! 

Someone unknown for a supposed couple of hundred bucks savings wouldn't be worth it.

You can't refi for an unknown period of time, probably a long while.  

The biggest unknown on being able to estimate cost is obviously the land.

Hi, my name is Corbyn Doyle and my wife and I live in central OKC.We are totally new to REI, and have come to this site looking for helpful knowledge in assessing a couple of deals that have been offered to us in our neighborhood.They are both owner-financed deals on rental properties just down the street from us (one is a duplex and the other a duplex with two garage apartments).Both deals have kind of fallen in our lap (we weren't looking for investment properties) because of our friendships with the two owners of the properties (a different owner for each property, unrelated and unknown to each other).We basically need to know (1) what kind of return on investment we could expect from the properties (given certain known variables) and (2) what sort of pitfalls to look out for in owner-financing.Thanks for any help you can provide!

Rental's will be different.Once I am done with my "estimate", I usually add about 10% to that number for "unknowns".

Original loan $47,900, 10%, 180 months, $514.74 payment.1st position, 85 months, $514.74 payments. 28 paid, 3 in arrears $1,544 + $640 taxes ($2,184)2nd position, 85 months, $514.74 payments.FMV unknown, county tax appraisal is $26,238.

Mike LaCava, Yeah thanks Mike The 70% rule is how I am running my numbers, although, I do believe I need to be a tad more conservative with my numbers to count for the unknown.

Is it a good idea to ask the mailman and/or code enforcement officer to let me know of any houses they know of that are vacant, for sale by owner, or otherwise potentially a good deal that is practically unknown to other investors?

Too many unknowns there.