Which camera are you trying to sell?
I have seen cameras put up on other HT sites and on some techie forums.... dont really know of a camera forum though...
You'd probably get more out of ebay anyway because if you go to a camera dedicated forum to sell it, you will encounter knowledgeable people who know how much (or little) the camera is worth and will drive you hard for a bargain.
Just my 2 cents.
If you need help selling on ebay - I have an over 100+ 100% positive feedback selling account that I can help you out with.
Joey