I love E-Bay.

I have had a few bad experiences:

I bought a second-hand computer, and it turned out that the L2 chip was bad (which the repair shop didn't discover for some time, since they thought it was a bad hard disk and replaced that first!) The computer was sold with no guarantee and I had already posted good feedback. :/

I bought a book once from an absentee seller, too--I paid by paypal, and a month later I hadn't recieved the book or any response to e-mails. I filed a complaint with both Ebay and PayPal. The book finally turned up a couple months later, with no explanation.

I bought a used expansion card, and the seller shipped it loose in a cardboard box, no padding or anything. It still worked, though.

Apart from that, everything's been great, and everyone's been good to me! And I've had around 130 transactions, most buying and some selling.