I've got an online friend that does the account selling for all his friends, and he sold a couple accounts for me about 2 years ago. He advertises through Craigslist and meets in person, and deals in cash. I think he has them come to his house, but I would meet in a LAN Cafe or wireless hotspot. (you'll need net access to log in to Battle.net and change the email and password for them.) For pricing, we just check craigslist for other postings of similarly geared characters of the same class.
We did sell our Warhammer Online accounts to some website not too long ago. We didn't get much, but that's a dying game and we were just glad to get something. I'll ask him what the site was and if they buy WoW accounts too.