Cable services and satellite services typically offer DVR services for an extra monthly charge (we pay something like $7 a month for DVR, at which point the HD DVR box in the den - which we pay the same rate for as for the HD non-DVR box in the bedroom - gives us "Tivo-like" capabilities). Tivo typically costs a bit more, but they are marketing their version or DVR software as a reason for the extra cost.
You can also get hard drive-based DVR units that are standalone and require no monthly fee. The principle difference is the "brains" behind them - a standalone box may not have the same ability to grab program guides and know to record new episodes of certain shows, for example. For a number of years, we used our Panasonic DVD recorder (a
DMR-E80 with built-in hard drive) to time-shift TV, but the trick was that I had to manually set up the timers to record shows. Of course, the flip side was that I could go through and edit out ads before we watched or even burn to DVD-R, although the 8 or 10 minutes it took me to cut all the ads out of an hour-long show (thus allowing us to watch that show together in about 42 minutes without needing to grab the remote) ceased to fit into any sort of daily schedule once our daughter was born...