Would second the SVS. I have looked at retail subs, I have had the SB-1000 in my house, and if you can, save the money.
Compared it with a more expensive Martin Logan from Future Shop, no comparison. Tighter bass, better extension. No one regrets a good audio purchase. Get the PB-1000 for movies and games.
The sub 12 will probably be your next best choice, seen a number of people recommend it in your price bracket. Good luck.