well, i think thoes are 500-600 rms right?? if so, look at the kicker KX1200.1 or i was reciently looking at the Phoenix Gold Xenon 1200.1 for a friend, they go for $400 on ebay. or you could look at Hifonics, they have several models in your price range on ebay.
I have the same set up. i was going to go with the hifonics bx1205d since they are overrated. I just got the Kicker sx900.4 and bridge 2 channels. Thats prolly out of your price range.