The best option will be a small mono that's 300-400w rms at 2 ohms.
Since it's a good quality sub I'd be inclined to lean more toward the 400w side.
Some good options...
http://www.sonicelectronix.com/item_22644_Clarion-XR2110.html
http://www.sonicelectronix.com/item_22381_Pioneer-GM-D7500M.html
http://www.sonicelectronix.com/item_9710_Infinity-Reference-1300a.html
http://www.sonicelectronix.com/item_18885_Orion-Cobalt-CO8001-CO800.1.html
http://www.sonicelectronix.com/item_21954_Kicker-ZX400.1-10ZX400.1.html