Working a seller-finance deal on an apartment building

[Michael K.]

I happen to stumble across an off-market deal that a lady is willing to seller finance an 18 unit apartment along with a duplex right next door ... 10/1 bed units, 8/2 bed units and 2/2 per side duplex in a C- neighborhood. I have basic figures written up and am working on coming up with a final offer to combine both units into one lump offer.

I am having issues finding a way to validate my numbers ... nothing in the area has sold recently, and the last time this building was purchased was 3 years ago for a substantially lower dollar value than it should have been, due to its pre-rehab condition.

Looking for a direction I could take to get a proper valuation so I do not overpay! I want my calculations to be as spot on as possible.

Any ideas?