I'll suggest the M&K KX10. Brand new on eBay for $240 shipped. Seller has sold 74 of these with 3 more remaining. I have this SW, use it in a small 2CH bedroom set - up. Sealed sub, compact, very musical, controlled output and perfect for you needs.
sleeper small subs stereo application
Contemplating Hsu stf 1 for 2 channel enviroment...no HT deep bass needed...is this the frontrunner in the 300 usd category? My main amp doesn't have pre outs...any other contenders? I understand audio nirvana is not available at this price point...my Triad sats go down to 80hz...small room...just looking clean, well articulated bass for lower octave