How to value a vacant 4plex?

[George Gao]

Hi, there is an expired listing for a 4plex in North Houston asking $200k. It's vacant and needs about $80-$100k (according to seller) of rehab work. The units will each rent for about $800-$1000/unit. The building is 4,140sqft, built in 1995, consists of 4 2bd/1ba units. But it's hard to get good comps with SFR in that area. Based on cash flow and 10 cap, I got to around $200k ARV. What am I doing wrong?