your sub's are 250 watt rms so feeding them 500watts each wouldent really be that smart..
The HiFonics Hifonics TXi7508 will produce 500 watts at 2 ohms so that would match your subs.
The alpine Alpine MRP-M500 is also a good choice.
look around for amps that produce 500-600 watts at 2 ohms and you'll be good...you cant really go wrong unless you buy some crappy brand like Dual or Sound Stream..etc.
Or you can feed them 500 watts each untill they blow..they are pretty cheap subs so you can prob get another pair.