If you don't wanna spend alot on a amp (which you will when it comes to kicker, jl, Memphis, Alpine, mtx, or any other large named amp, you will spend alot!)
But!! There is a solution! And it is HIFONICS
Look into the new (silver) hifonics Brutus amps, they are cea certified, so they are true wattage, they are 1 ohm stable, and really good priced!
You can get hifonics Brutus 1200 watt amp for about $150 brand new on eBay, and that will be plenty big enough for your subs.