Do you have NTL in the U.S. as a cable isp supplier? If you do just find someone who has recently transferred from modem to Cable.
I've just done this in the UK and am now the proud owner of 4 USBnetwork connection kits. When the engineer arrived to set the system up, the kit hadn't arrived by post so he supplied one. I have since had 3 kits posted to me by NTL.