ok iv foud you a few, when you say cheap whats your budget?
if you want new, i can offer a hifonics zeus ZXI 1008, 2x500rms @ 2 ohm or 1x1000rms@ 4 ohm (your subs will wire to that) rrp £170 I can do it for £140 for you
or if your happy with second hand, a Directed D2400 Mono Amp which is 1x1200rms @1ohm its going for £120 with a custom alcantara cover