Newegg offers the Polk Audio 300-watt 12" Powered Subwoofer in Black, model no. PSW505, for $200. Check out with MasterPass and apply coupon code "MPGAMER16" to knock it to $175. With free shipping, that's the lowest total price we could find by $25, although we saw it for $6 less in January. It features a frequency response of 23Hz to 160Hz, magnetic shielding, phase switch, and adjustable crossover.