Estimating ARV on 5 plex

[Ben Baye]

I am looking at a 5 plex in a small town in northern wi. The deal is:

5 - 2 bed 1 bath units renting at $500/ unit at full occupancy currently with month to month leases. Asking price is $100,000. Some tenants have lived there for near 30 years. Based on pictures I can't see any major renovations needed but I'm confident it needs something at this price. My lender will do 80% of purchase and 100% rehab then refinance at 70% ARV with a 20 year note at 6%.

I’m considering trying to do 1 year of owner financing and covering the rehab then doing refi. I would like to hold it 2 years, up the rent to current rates of $600-$650 then sell it. 

I am not experienced in determining ARV on a commercial property like this. And given there aren't many comps how would I evaluate this property?

Thanks for the help!