Newegg offers the Polk Audio 50-watt 10" Powered Subwoofer in Cherry, model no. PSW10, for $79.99 with free shipping. That's tied with our mention from last December in another color and the lowest total price we could find now by $49. It features a medium-density fiberboard enclosure, frequency response of 35Hz to 200Hz, and line-level and speaker-level inputs.
Update: Specs corrected.