The best ones handle a range. I don't want a mechanic who's too good to touch my commuter bike, but I don't want a dude wrenching on the expensive Campagnolo bits on my road bike whose experience primarily consists of bashing stuff together on fixies, either.

I really miss my shop in Italy - that guy occasionally worked on pro's bikes. Like the guy who won a gold medal in the olympics. But he always had time for me, and whatever bike I brought in - whether it was the rusty commuter or the nice bike I'd bought from him.

I would never consider buying a bike on line. They're always going to need maintenance and having someone who knows what they're doing is worthwhile.