IME, brick and mortar stores are generally horrible places to buy used equipment. Prices over twice what the market calls for, sitting in a case with no body cap, no record of service, no warranty, nobody who can tell you a thing about the equipment, etc. Samy's here in L.A. is one of the most vile offenders. I have to wonder: Do they ever sell any used equipment there? If they do, who exactly is buying it? I am sure there are shops that are exceptions, but I have never seen one.
One of my only moments of weakness with buying used equipment from a camera shop: I decided to bite the bullet back in Jan. and pay $200 to replace my FD 200mm f/2.8 IF that I had dropped on a rock on the banks of the Mississippi. (The lens was the closest lens I have to being dead mint, and of course I go and drop the camera it is mounted on.) Glass was all fine, but the mount broke off and I lost some tiny screws and an important coupler of some kind in the mud, so could not put it all together again once I got to VA. Penn camera in Washington happened to have the same lens in decent shape, and I badly wanted it for the next day, so I forked over the green. I was just glad they had the 200 fixed lens, which is one of my favorite and most useful lenses. My other options were one of two 70-210 f/4s, and they were only $80 a piece, but I knew they would just be stop-gap lenses, and I would eventually either replace the 200 or get it fixed anyhow. I can't believe that desperation on the buyer's part is the only way camera shops sell used equipment, but it is certainly the only way I have ever bought it from one.