I'm considering finding a rehab investment. So, I went through all the sales in the area I'm looking at in the past year and characterized each house as A (updated), B (dated but well-kept), C (functional but not nice), D (no interior photos), or F (not livable). Due do the nature of the housing in the area I also split these up by number of attached sides. The clustering on A/B houses made a pretty good-looking line on $/sqft vs sqft, so that makes me pretty confident in what one can get for it. The rule of thumb I've seen is you don't want to spend 70% of your after-repair value on purchase, taxes, and repairs. Download the local cost vs. value for high estimates on the cost of repairs.