100W Portable Subwoofer With 4 Inch Bass, 4 Ohm/8Ohm Volume, And 4 Layer Voice Coil For Jl Audio 6.5 Speakers, Home Theater, DIY Model 221101 From Ning04, $31.53 | DHgate.Com
Amazon.com: Pyramid 8 Inch Car Subwoofer Speaker - 350 Watt High Powered Car Audio Sound Component Speaker System w/ 1.5 Inch High-Temperature Kapton Voice Coil, 89.2 dB, 8 Ohm, 50 oz Magnet - Pyramid PW848USX : Electronics