I've bought quite a few things off Ebay. My PowerMac G4 350 Mhz, paid $129 for that including freight, thought that was a pretty good deal. A second hand dealer here in Darwin has the same system (but with 64Mb of RAM, mine has 192Mb as well as a extra 10Gb HDD) with a 15" CRT monitor for over $500. A Mac compatible USB wireless adaptor for $20 (including postage), works a treat. Some mineral foundation that's $35 in the stores for $20. Found a supplier of henna based lip makeup that stays on all day and you don't notice you're wearing, $12 each. Some baritone electric guitar strings that sound a treat on my guitar (definitely getting more of those ) and the odd old Watchtower publication, waiting on delivery of a copy of 'The Divine Plan Of The Ages' that I just bought. Pictures show it to be in very good condition, it was printed in 1908 at Alleghany.
All up, I'd say my exerience with Ebay has been quite positive.