I have an mtx amp that does 1000 watts rms at 2 ohms. One sub i am looking at is the Alpine 12" Type-x sub. I am looking for a good quality sub that doesnt cost TOO much.
500$ is quite a high number to start with. You may want to look Image Dynamics, like the IDQ v3 12". Great sub.
JL Audio is also one you should look at. The new w3 line is spectacular.