The good thing is it would be under budget because I already have a nice stereo system.

get a JL sub, W3 or greater. Alpine monoblock amp, and get a wiring kit with 6 gauge power cable and ground wire(for future upgrades)

if you want more then get 2 W3 subs and a stronger monoblock amp, JL W3 are best pushed by 500 watts, so if you wanna have 2 get a 1000W monoblock amp.

If you install everything yourself it will be just about at your price range, if not a bit cheaper. Make sure to get a dual slotted box for 2 subs(a box that doesn't share air space) and if you are getting one sub then go for a single slotted box.

Im probably going with subwoofers build ty though.

I got some drag I forgot what its called bur it beats n no rattle