Data World Distribution via eBay offers the refurbished Motorola SURFboard DOCSIS 2.0 Cable Modem, model no. SB5101, for $15.95 with free shipping. That's $24 below the lowest total price we could find for a new unit. It features data transfer rates of up to 38 Mbps.

Note: A 30-day warranty applies, although it's unclear who backs it. Also, this modem may not be compatible with all service providers.