Newegg via eBay offers the Klipsch Synergy Series 300-watt 12" Subwoofer
, model no. SUB-12HG, for $169
with free shipping
. That's $19 under last month's mention and the best price we've seen. (It's also a current low by $91.) It features a 12" down-firing driver, frequency response of 24Hz to 120Hz, 300 watts of continuous power, and adjustable crossover.