Basically you can rent a wireless router from comcast for free- just pay $10 shipping (retail $100+)
If you currently lease a router from Comcast, you can keep your existing router and your monthly fee will be discounted to $0 a month.
You can get a Netgear WNR3500 router from Comcast if you are a current customer of theirs. The router normally costs $100 or more, but you can get it for $10 through comcast (free with $10 shipping)
https://www.comcast.com/wirelessrouter/default.cspx?403;https://www.comcast.com:80/wirelessrouter/