Motorola SB6141 SURFboard DOCSIS 3.0 Cable Modem for $77.75 shipped.  Here is a screenshot for reference. It has IPv4 and IPv6 support and speed up to 160Mbps.  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 and this is also a better cable modem than most modems from ISPs.  Most places have it for about $89.