if you don't want to pay as much you can always run the mtx 4000 series these are good and only about $50 each. I had 2 10's and my friends tought I had 2 12's and it would set off alarms that was with a bazooka amp that would do 500rms and a custom box I built for them. But don't put an amp that has a higher rating
Another good quality are the alpines. But the most important thing is the box it must be good one and meet the subs space requirements. You may have the most expensive sub but if the box is crappy it won't sound like it should!