No way he's getting a Cross-check or San Jose for $500 or less without a lot of Craigslist karma.
Bikesdirect seems like the obvious choice here. The previously mentioned FCU and the Kilo WT look good.
Your LBS will have some SSs for around $4-500, but generally speaking these are gonna be hybrid-y models like the Soho. Cool if you're into that, but I'm not.