Newegg via eBay offers the Motorola Arris Surfboard 600 Series DOCSIS 3.0 Broadband Cable Modem, model no. SB6183, for $84.99 with free shipping. That's a buck below our mention from twk weeks ago and the lowest total price we could find by $15. It features download speeds of more than 600Mbps and upload speeds of more than 100Mbps.
Note that this modem may not be compatible with all service providers.