Integrated TV Tuners and Recorders
There are a number of TV Tuners that allow for PVR style recording. Some are relatively free from the limitations that you tend to see in many of the more high profile projects (like an inability to move recordings from the device or playback on multiple network connected devices).
Search for products described as "Linux Enigma 2 Receivers" for example. These will often be available from a number of generic sounding Chinese "brands" but can meet many of the goals described in the DIY PVR project.