I love the idea... the concerns would naturally be liability, meeting building codes, safety codes, local occupancy requirements, deadbeat builders, etc... Then there's the question of how big the market really is. I know there was a store here in Seattle ("The Wooden Boat Store") that sold to that market. It went under a few years ago and is a bike shop now. I would think a good real estate attorney could tell you the viability given local laws. Otherwise, given a motivated owner, you could just do an all cash business on the side... run out the back door when the inspectors come

In New York City, artists move into those spaces illegally and then, over time, the politicians are forced to grandfather them in as legal occupants. The neighborhood eventually gentrifies and, before long, you have fancy restaurants on every corner and soaring prices. That happened in Greenwich Village, SoHo, Tribeca and, from what I hear, is now even happening in Brooklyn.