They're rated at 500 watts RMS (never pay attention to max rms) so you want one 1000w rms amp.
Alpine offers GREAT amps at really good prices.
Here's the amp I'd recommend.
http://www.alpine-usa.com/US-en/products/product.php?model=MRP-M1000
Best Buy offers this amp at a better price. Check Crutchfield.com as well.
If you get this amp, wire the subs at 2 ohm.
