Most cable companies charge at least $3 per month for your modem, which adds up to $36 per year. But there's no law that says you have to lease their modem; BYO and you can pocket that cash instead.
You'll start recouping your investment around month seven with the D-Link DCM-202 cable modem, currently on sale for $19.99, shipped, after a $20 mail-in rebate.
Before you buy, you should call your cable company to make sure they support the DCM-202. But judging by the roughly 400 Newegg buyers who rated this modem 5 out of 5, compatibility isn't an issue. And while I know many of you detest (or at least don't trust) rebates, you'll still end up ahead even without it.
The bigger concern is getting your cable company to stop charging you for their modem even after you turn it in. Keep a close eye on your bill after making the switch.
The rebate deal ends January 31.