It's $199 and only available in selected markets through DirecTV: TiVo HD DVR. As far as I know, it is not available in stores.

DirecTV Web page:

There's surprisingly little detailed info about what features are included and what they left out in comparison to a current stand-alone TiVo, but I ordered the DirecTV TiVo HD DVR today so I'll be able to provide all those details in the next few weeks. Hopefully DirecTV didn't cripple it too badly and at least the price is not as bad as I feared. Certainly worth checking out. Like I said, I ordered mine already.