What else is there besides eBay?

[MegoNinja]

I would like to know if there is any place I can go for collectable shopping online that is not eBay. Sometimes eBay just does not cut it, I cannot find what I want and it is just plain annoying, especially if I want to buy something common and basic but nobody out there is selling it. Is there like a collectableauction.com or something.
Please help me out, unless you want to keep this 'auction' site a secret and buy all the stuff yourselves