First deal analysis

[William MacBride]

This is kind of the first potential deal me and my girlfriend have run down and are trying to decide if its a "good deal." I'm just putting it out there for anyone to comment on in whatever way they see fit because I'm so new to real estate.
It's 2 houses in a not that nice neighborhood in Buffalo, N.Y. They are "two detached houses." one has 2 bedrooms and 1 bath. The other has 1 bedroom, one study of some sort, and 1 bathroom. I haven't seen them yet but they must be pretty tiny. He wants 18k for both of them together.
He says he rents 1 for 280.00 a month (the 1 bedroom), and has someone lined up to rent the other one for 500.00.
The PITI on the 5 year (seller financed) note plus the utilities he pays (water and garbage) comes to about 450.00 a month. The two rents together come to 780.00. So positive cash flow of 330.00.
Its near a state university (buff state), but is not exactly in a nice neighborhood. It looks sort of like we'd be in for slum lord hassles to me, but I donno. It's just a low income area, not exactly a slum probably.
My girlfriend says zillow.com gave a FMV of 39 grand. It seems unrealistic to think we could even flip it for 30 grand if this guy's willing to let it go for 18k. Why would he do that?
Haven't done any comps on it yet.
any thoughts?

Will