So I've had cameras and DVRs at my house for many years. I've always tried to put together a cheap system, and I've never been completely satisfied with it... Hard to search for recordings, non-intuitive interfaces, downloaded video files that can't be played by any normal S/W... But recently, I decided to take a chance on a $51 mini DVR, 4 channel, direct from China. It arrived quickly (less than a week) and I installed a 1TB $49 WD SATA drive, and got it all setup.
The improvements over my previous cheap 3-4 year old no-name Ebay DVR are significant. Recordings are shown on a horizontal timeline, searching is more intuitive, the web interface is much better (after you figure out how to install the unsigned Active X), and you can even download video through the web interface as AVIs! Very happy with this super cheap DVR. Now to buy another for the garage. Also has HDMI output.
Search ebay for "mini dvr 4 channel h.264"