Newegg offers the refurbished Logitech Z213 2.1-Channel Speaker System, model no. 980-000941, for $17.99 with free shipping. That's the lowest total price we could find for a refurb by $7. Features include 7 watts RMS power, a 4" down-firing subwoofer, 65Hz to 20KHz frequency response, and 3.5mm audio input.

A 90-day warranty applies, although it's not clear who backs it.