While back for $100 dollars you could have a pretty decent subwoofer. Too bad they don't sell it anymore. It is a KLH subwoofer, Model is GFX600. J&R used to have it but not anymore. It went for about $79 dollars on clearance sale.
Its a 10" driver in a 4th order bandpass box with 125w max output from the bulit-in plate amp.
Even though the subwoofer itself is very "flashy" looking it is pretty good. Very deep extended bass, the subwoofer speaker itself is an very efficient high quality design similar to more expensive subwoofer. It has just about enough bass to make your walls vibrate if you really wanted to turn it up.