If you just want a single 12" sub, perhaps try this - TS-W309D4 30cm 4
I would suggest a single 12" (or 10") that is dual 4ohm, so it can be configured to present a 2 ohm load to the amp.
Then for an amp, something like this:
GM-D9500F Four Channel Class-FD Car Amplifier (800W) -...