If you need a website don't you need to buy domains? Or are you looking sell domains? If you looking to sell you can check out DNForum.com and Namepros.com. They are domain name market places but not sure if that's what you are looking for.
Ya... except it's so much trouble to sell domain names at digital point. I use to like selling here but with all that crazy verification thing which I can never figure out I finally gave up. Especially when you just trying to sell a $5-30 domain that has less than 20% chance of selling it's not worth the time. I like the old itrader and domain section for digitalpoint much more quite honestly.
As seen on the NamePros forums GoDaddy, NameCheap and Sedo Auctions seem the most common marketplaces for domains/sites (the actual NP forum also has such a section)
Your best bet to get a good price for a domain is selling it to someone that visits your domain to see if it is available. Make sure you have a contact form and a message on the domain indicating it is for sale.