Motorola SB6183 SURFboard DOCSIS 3.0 Cable Modem for $79.99 shipped. Here is a screenshot for reference. This cable modem features IPv4 and IPv6 support and speed up to 686Mbps. This is a relatively high-end consumer cable modem and is on the approved list of major cable ISPs. Having your own cable modem often means you do not have to rent one from your internet service provider (ISP) with a monthly rental fee, which saves money in the long run. Most places have it for about $109.