$150 shipped I will sell you my Kicker ZR360. Its actual output is 550rms @4ohm mono and 725rms@2ohm mono. It will do your sub justice.
Carsound tested and reviewed this model:
http://www.carsound.com/reviews/amps/zr360.html
Let me know.
EDIT: My bad, your looking at a 4-channel amp. I quit reading after you listed the sub I guess. lol