FriendlyNudist
CAG Veteran
Gameboy Advance in Indigo for 44.99. About 20 dollars cheaper than anywhere else I've seen it. The catch is you have to buy a game with the system. They also have some different bundles and stuff. I can't vouch for the site but it seems like a good deal (unless I'm missing some fine print). I'm seriously considering picking it up for work but I think I'm going to hold out for an SP.
http://www.buyritegames.com/product_information.asp?number=GBA-SYSIND&back=yes&dept=1127&last=1013
http://www.buyritegames.com/product_information.asp?number=GBA-SYSIND&back=yes&dept=1127&last=1013