I think Narcodog has it right. A local shop would go bankrupt trying to maintain a full inventory. It's just like a lot of other retail stores. They can't compete with a mail order business especially when you factor in ordering over the computer.
The only limitation there is that you don't get a "hands-on" examination of the material.
My personal solution has been to only deal with mail-order shops that have 100% return policies.
Good luck.