I have a Motorola Surfboard SB5101 cable modem I no longer need. These usually run about $60 online and are a great way to avoid another monthly charge to your cable provider.
I'm selling this one for $20 because I cannot find the power cord. The writing on the back says it takes a +12VDC connector. Shipping is an extra $5 or you can pick it up in the northern Virginia area.