Walmart offers the Motorola Arris Surfboard 600 Series DOCSIS 3.0 Broadband Cable Modem, model no. SB6183, for $89.99 with free shipping. (Amazon charges the same.) That's the lowest total price we could find by $6, although we saw it for $15 less two weeks ago. 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.