I just bought the CMD31T tonight, 3/21/2012, at Fry's for $89. I noticed a lot of online places have it for $75 +/-. Don't know why you were having a problem finding it for purchase anywhere? I bought it to replace a 5-year-old Motorola Surfboard from Cox cable. So far this thing screams WAY faster than the Surfboard. I'm also running a Netgear N router, dual band, dual radio (WNDR4500 maybe?), so the 2 seem to work better together than other setups I have had. I have 16 different things running off the router. 4 wired and the rest wireless. No problems, but of course all 16 things aren't running at once. We can have like 6 or 7 things running at once though and there's no degradation to the connection. For instance, we'll have 3 laptops, 2 Roku's and an Xbox, all wireless, running at once. No problem and the Roku's are still getting HD performance.
EDIT: Well, here we are 2-20-14, nearly 2 years after I bought this modem and you know what? It's still going strong and running perfectly fine! I had some issues for awhile, but it turned out to be Cox Cable and not the modem. I switched back to the old Surfboard and it acted the same, so I knew it was them? Lots of drop-outs and shutting off for minutes at a time.
The only change I'm looking at now is that there are new models out that get twice the throughput that this one does? So I may upgrade to one in the future? The newest Motorola Surfboards are getting the highest ratings, and if you are interested, make sure to thoroughly research them? They are not created equal by any stretch? Even a single model number from one to the other has vastly different features and results! I forget the exact model numbers offhand, but say you're looking at the 6120 and the 6125, they can be completely different beasts even though they are in the same model family? A Volkswagen vs. a Corvette kind of difference.