Quick Ship via eBay offers the refurbished Netgear CM500 DOCSIS 3.0 Cable Modem for $29.99 with free shipping. That's $10 under our November mention for a new one and the lowest price we've seen for this modem in any condition. (It's $30 less than a new one today.) It supports 16 download and four upload channels with speeds up to 680MB/s. It's certified for Comcast Xfinity, Time Warner Cable, Cox, and Charter, among others.

Note: A 1-year Quick Ship warranty applies.