I got my PS3 from eBay. It worked out allright. Just make sure you look at the seller's feedback and see if he's sold at least somewhat expensive stuff before and delivered on it.

My only gripe was that I think I paid for the 80 GB version and ended up with the 60, but I think that the person selling it to me honestly thought he had the 80 GB version. Meh, oh well. Works plenty well for me.