+1 on what Martin wrote. I've bought a couple of things on ebay that turned out to be not such a great deal, I'm thinking of a couple of cell phone chargers in particular but they were so cheap that I really can't complain.

If you can find a vendor on ebay that delivers what you need at a good price, treasure them.

And for that matter, there are any number of online businesses outside of Amazon and ebay that give exemplary service. I haven't purchased anything from them yet but Redflare, a member/vendor here on ETS gets very high praise from their customers. McMaster-Carr, an industrial supply house sets the gold standard in my opinion for their variety as well as there incredibly fast shipping and very reasonable shipping rates, I can order from them on a Monday afternoon and the box will be sitting on my porch in less than 24 hours.