do that include JUST the sub or amp? Or do you need a box and wiring? Are you going to build a box? How many subs and what size were you looking for? Need more info.
a lot of ppl are going to reccomend RE subs, but im going to be different, get this 1 kicker comp c15 svc4ohm, and kicker kx200.2 amp that'll be about $200, then build a nice ported box and you'll have a pretty decent system for cheap.