MTX Audio offers its MTX Mobile 12" RoadThunder Series Subwoofer, model no. RTS12-04, for $69.99 plus $4.99 for shipping. That's the lowest total price we could find by $22. Features include a polypropylene cone, 2" voice coil, 250 watt RMS power (500 watts peak), 27Hz to 150Hz frequency response, asymmetrical linear drive system, and more.