Ending today, Polk via eBay offers the Polk Audio 300-watt 12" Powered Subwoofer for $199.99. Coupon code "PSUMMER20" cuts the price to $159.99. With free shipping, that's tied with last month's mention and the lowest price we could find by $40. It features a frequency response of 23Hz to 160Hz, magnetic shielding, phase switch, and adjustable crossover.