What is a good RMS Wattage for a 2 channel amp for a "pair" of 12' subs?

I have a Sony Xplode 1000Watt amplifier 2channel and I dont know the RMS but somethings wrong with it....MMk well I want a new amplifier and I dont want to spend alot on a new Amp, but I want something powerful. I have dual 12' MTX Audio Thunder Series subs and want to make it sound good. Is 250 RMS x 2 channel good? Please help me out here, I need a deal, and a working amp.