altho it's possible to compete with ur friend with $500, i'd save up another $200 for a little leeway. sounds like ur more into spl or at the very least sql, so u'll want subs that'll produce a lot of sound. here are a few choices that u might want to consider:

-fusion powerplant
-autotek mean machine
-power accoustic **** (no exp w/sub, but blue ledz will help out)
-60/40 sub (sq/spl): edesigns k-series (awesome sub!) don't be fooled by the "60/40" either, they can get pretty loud

the above can be found pretty cheap... now for amps:

-edesigns nine.1 (again, no exp but good company and amp is $275)
-jbl bp600.1 $195