IME, ebay is a good place to buy used records. One thing I would say, though, is not to pay any attention whatsoever to feedback, unless it is very bad. There are many great sellers on there who's feedback ratings have been damaged by idiots. That said, there are many bad sellers on there, too, who have great feedback ratings. So I don't pay any attention to it. If I have a good experience with a seller, I go back to them again, and if I don't, I don't. People get way too worked up over the feedback rating stuff. I have been happy with almost every transaction I have had there, and the one time I wasn't, the guy made me a great deal on something else (the problem was not something he could rectify), and I bought from him again later.
