So you really just have a few choices i looked into this quite a bit bascially i wouldnt go lower then http://www.amazon.com/Polk-Audio-10-Inch-Powered-Subwoofer/dp/B0002KVQBA/ref=sr_1_6 nice 10in polk 100 bucks hard to beat if you want a little more umph which i did get either the http://www.amazon.com/BIC-America-F12-475-Watt-Subwoofer/dp/B0015A8Y5M/ref=sr_1_1 or the polk http://www.newegg.com/Product/Product.aspx?Item=N82E16882290130 http://www.amazon.com/BIC-America-F12-475-Watt-Subwoofer/dp/B0015A8Y5M/ref=sr_1_1 Of the later two i would get which ever is cheaper i got the psw505 because i got in open box item from amazon for 160 havent seen that price again, if it wasnt for the price i would have gotten the bic. You could always blow things out of the water and get one of these http://www.svsound.com/products/pb13-ultra