As wallace says, its the best bet; buy all the shops and just the expensive houses, after buying every house in bowerstone (market, industrial, old quarter) and brightwall and then them hitting 0% it was so frustrating to have to fix them all. Not money wise as i was rolling in it, but simply time consuming and annoying. Feature needs to be implemented IMO, not that it will.
Sell em all, tis what I did.