Interestingly, the Click and Clack Brothers of NPR fame had a DIY garage back in the 70s, as alluded to in this (articles.latimes.com)article that worked very much like this concept. It evidently morphed into a full service shop along the way. Basically, not everyone has the special wrench to pull out a steering column, and they'd rather pay someone 60% of the cost of that wrench to rent one for an hour. Along the way, there were guys in the garage who could help out with advice on the best method for disassembly / reassembly / etc.

This also has the distinct feel of a Makerspace (seattlemakerspace.wordpress.com), which has gained some prominence in the last few years. It's very expensive to have a 3D printing machine in your own home, but it's not so bad if you spread the cost over 50 dudes who all want to print their own Settlers of Cataan tiles and have a membership to the shared workspace.

Ultimately, though, these ideas all seem to orbit around the concept of a Cooperative, which is a time-tested, mother-approved business model for things like electrical power distribution, grain storage/sale, etc. The trick to success, it seems to me, would be the skill to identify your target audience and then build sufficient cohesion to keep them from imploding until some commercial success can be seen. That, however, seems to be the crux of most successful businesses, regardless of the venture.