As a Michigan resident who has tried buying property in Detroit... many of the cheap plots of land come with huge fines and back taxes attached. The owner stopped paying taxes, and when the fines added up they skipped town. If you buy that land, it's now your responsibility.

Not saying not to buy land in Detroit, there are lots of businesses making good money on cheap land (and there are quite a few startups, especially around Woodward Ave, see: Dan Gilbert). Just make sure to do your research to keep away from any nasty surprises. That $25 half-acre with a plant already built might actually cost $100,000 up front.