Sonic Electronix offers the NVX 600-watt RMS 12" VS-Series Dual 4-ohm Car Subwoofer, model no. VSW124 v2, for $139.99. Coupon code "PRICECUT15" drops it to $119. With free shipping, that's $51 off list and the lowest total price we could find. It features a 2.5" aluminum voice coil, dual 4-ohm impedance, and an 11.63" mounting diameter.