To understand why the answer to your question is as it is, it is important to understand some background: VHS recorders were introduced in 1977. Back then, they used to cost upwards of $400 each, back when $400 was much more so a lot of money than it is today. Then, the technology became, literally, cheaper and cheaper (i.e., both in terms of lower price and lower relative quality). There were still high quality VHS recorders, but they were providing neat-o features and higher levels of picture quality that the average person didn't really care about.
We are still at the very beginning of the technology curve for digital video recorders. For example, the Sony DHG-HDD500 was introduced in 2002. So, we have not yet reached the point where digital video recorders are getting "cheaper and cheaper" in any dimension. So what you can expect with regard to purchasing a digital video recorder is roughly the same as what we had available to us eight years after the introduction of JVC's first VHS recorder -- so basically put yourself back to the mindset you had purchasing a VHS recorder in 1985.
Okay so so much for background info... the short answer to your question is that you can expect to pay between $250 and $600 to get a digital video recorder, and to get one that is relatively trouble-free then you're looking at that $600 number, not the $250 number.
The $250 number reflects a device like the DTVPal DVR. It is a basic device, originally put out by Echostar, and now put out by Channel Master. I do not recommend it at all. It has been plagued with problems, most of which have been resolved, but some haven't, and the various turnovers of ownership, and where the product line has ended up, leads me to distrust further support for the device. From some of the messages I've read this week, I fear that if you go with the DTVPal DVR, you may end up having to deal with problems that actually won't have resolutions.
The $600 number reflects a device like the TiVo Premiere DVR with lifetime service. To get that $600 price, though, you'll need a friend with a TiVo. Otherwise, you'll pay $100 more. The TiVo is an excellent device, with excellent ATSC tuners, and is useful for a lot more than you need it for, but you may find a use for those features regardless.
Let me know if you want more information on either of these options.