I know there's probably a forum thread on this subject somewhere, but I couldn't find it. Any suggestions are greatly appreciated. Thanks.
There seem to be fewer of them every day. Paradox Playground just went out of business about a month or so ago. Try:
D&J Hobby: http://www.djhobby.com/
Game Kastle: http://gamekastle.com/
Gator Games: http://www.gatorgames.com/ (San Mateo, quite a ways North)