Yes, eBay and Amazon probably get the most traffic of any auction sites and this is an advantage that can't be ignored. However, there are other auction sites that may be worth a try - Craigslist, eBid, Overstock, Online Auction, BlueJay, eCrater, Bonanzle, and lots more or via your own store or website if possible.
Here's a post that you might be interested in reading:
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Also, a quick search in the forum for eBay alternatives may bring up a few places.