Ebay or Craigslist, i would try craigslist there are no fees to sell there so the seller will probably give you a better deal, try to jew people down, then meet them at a starbucks or their house. ive done tons of deals on craigslist with no problems.
Ebay is good as long as you find a seller who has a lot of feedback and its in the high 90's (positive feedback of 97percent or higher) is a good indicatin of a solid seller who won't rip u off.