Bah!
I was hooked on E-Bay when it came to getting out-of-print books and such for a Role Playing Game I'd owned for years, then I found that Amazon could be just as inexpensive and infinity times more reliable as far as actually getting what was described in the original solicitation to buy.
I never got totally burned on eBay, but I had more and more "almost but not quite" stuff turning up when I bid (usually with "buy it now" since the oft-mentioned sniping software would otherwise drive the prices into the stratosphere).
I suppose I could have used such software myself, but having to give someone else credentials that I carefully selected to be secure seems a bit...counterproductive and time consuming, as to be safe I would have to replace the credentials right after an auction in order to be "secure" again.
As for the costs, it's always been 'whatever the market will stand". If people stop using the service, the prices will drop again. But they won't, because - when you get down to it - the prices aren't outrageous enough.
Yet.