How many watts does my amplifier need for my subwoofers?

I am going to buy 2 12 inch JL Audio 12Wov2 and i dont know how many watts my amp needs to power them. the subwoofers have a rating of 300 RMS each. so i want a powerful amp. i am not trying to spend more than $400 dollars. i also prefer the brands rockford fosgate and JL Audio. here are the subwoofers i want http://www.crutchfield.com/p_13612W0V24/JL-Audio-12W0v2-4.html?tp=111&nvpair=FFBrand%7cJL+Audio&tab=features_and_specs. can someone please help me find the right amp.