Jim, I'm sort of a video surveillance geek, and I have a good friend who owns a surveillance company who sells/services/installs camera systems. He lets me test a lot of the stuff he sells at my home and/or at the cigar lounge.
Immediately eliminate from consideration all the systems you can buy at the box stores from companies like SWAN, etc. Those systems typically use cameras that are several generations old and often are proprietary so you can't add more hard drive, or if it goes down you have to send it in for service instead of having a company local to you fix it, or swap it on the spot.
A base model hybrid DVR recorder, for an 8 camera system, capable of doing both low quality analog and higher quality IP is probably right around $1200 to $1500. (prices are constantly dropping). Analog cameras (1000 TVL) will cost you about $100 each. IP will be double that, but resolution is exponentially higher. Again, we are talking basic system.
You can actually get fancy systems that see movement through fog, but you'd need BigAl's budget for some of those features.
I own 2 different systems that cover my property and have 23 cameras, and I back those up with several infra-red flood lights to extend the night viewing range. Oh, and whatever "range" the camera says it will cover at night, cut that in half. If it thing says its IR is good for 75 feet, honestly the best you can expect from it is about 35'-to-40' of useful image at night ... unless you also put out infra-red flood lights, then you can light up the area with 'invisible light' and get a lot more night time range.
