[T.G]

It's been a number of years since I looked into security video surveillance systems, I don't know whether this is still the case or not, but at the time, low cost (anything under about $1500-1700) systems were best avoided if you were serious about it.

A lot of this stuff, even the cheaper systems, looks ok on the in-store demo where everything is brightly lit and the camera is trained on objects only a short distance away, which is great if you want to video in your retail store, but that's not your real-world.

The cheap cameras typically don't give a clear enough picture, especially at distance and/or under lower light conditions, to identify someone and the lower end DVRs don't record at a high enough resolution to zoom in on playback. Good low light & no-light cameras will also cost you a bit more.

Something else to look at is the DVR's ability to offload the data in a useable format. Does it have a DVD burner built in or not, can it transfer files to your computer, do you need proprietary viewing software or is it a standard mpeg-4, etc...

Lastly, remember to check local laws about security camera footage and it's admissibility. You might have to meet certain conditions, ie: put up signs indicating that security video is being recorded, if you expect to be able to use the footage in a legal matter.