I was just on estarland.com and noticed that they just initiated this sale in honor of the World Cup. According to the sales page, the sale ends on July 4th.
They've got a large selection of retro and new games on here and the prices aren't that bad for most of the games. For those of you who may not trust them, I have traded in several games and purchased several games from them without a problem. They have some of the best trade in prices I've seen and the credit can be immediately used towards another purchase even before you ship it to them (as long as you've got a credit card on file).