Newegg via eBay offers the Motorola Arris Surfboard 600 Series DOCSIS 3.0 Broadband Cable Modem, model no. SB6183, for $79.99 with free shipping. That's $5 under our May mention and the lowest total price we could find by $13. 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.