Does a subwoofer amplifer exist?


I am in the process of building a sealed subwoofer and I am in the middle of searching for an appropriate subwoofer amplifier. I would prefer not to get a subwoofer plate. I have searched for a subwoofer amplifer with a built in crossover, but so far I have not been successful.

Does such a thing exist?
matchstikman
hsu,nht,dbx,m&k,all 4 of these manufacturers make subwoofer amps for passive subs.

mike.
If you decide to build your own sub, rather than buy one, then you might want to look at Outlaw Audio's M2200 monoblock amp, which sells direct (via Internet) for $325. For more info, go to this link: http://www.outlawaudio.com/products/2200.html

You may also want to consider just buying Outlaw Audio's powered subwoofer, which was designed for them by Hsu. It sells for $579, and has gotten some excellent reviews.
Wow, these amps aren't cheap. Why are they so much more expensive than a subwoofer amp plate? The Outlaw amp has a good price; however, I would still need to get a crossover, possibly the Paradigm unit I see on Audiogon on ocassion.