The most trusted site for account trading is realpoor.com They have a strict policy regarding interaction and how you contact people to ensure that if someone tries to do something underhanded, that they can prosecute them and get your money/account back. A couple of players I know know have traded on this account, and it is first rate.
Another easy way to sell locally is by using craigslist.com. You choose your city and state and you can post ads for free. In the ad you can give your phone number or even just your e-mail. Be prepared to answer in detail about your WoW account.
You can also set it up on Ebay and try selling it there!