Or try to do private sales.

Try Sedo, their one of the biggest sites for buying and selling domains and websites.

Well I am also Looking a place where I can sell my domain in best price. I have not tried anywhere instead of namecheap.com. Thanks for guiding through out.

you can try digitalpoint.com forum or flippa.com

try selling it private if you got contacts in the industry thats always a good money

Well there is a new service it call bido it a vote for auction domain name but you will not get really good price for it. Next one in line is "Afternic". And obviously you already try sedo and and ebay so i don't really have to mention it.

ebay is a good place to sell