ClassDAudio.com several options. Solid bass control. Overbuilt is an understatement. Yes, I know. Small operation, etc. Not going to argue with anyone. Have two. Pleased. Buy them new and you will be well within your budget. Great support.
Class-D recommendation
Looking for a class-D recommendation for the base portion of a multi-amp system w/ active xover. The amp will be powering a pair of 15" 4Ohm woofers from 30 - 600Hz. Need at least 400W, very high damping, and clean into the midrange. Everything above 600Hz is taken care of by a class-A amp. I would prefer to spend <$2k used.