From a Network and Computing point of view this is Not a Big deal.
There is a lot of Software that can detect movement store, publish or what ever the camera signal (some is even free) check any shareware site for webcam and you can choose what you like.
The problem is the Cameras.
The inexpensive simple Cams are great, but they are USB. I.e. the cables has to be around 15? max.
There is Wireless Cameras, they go for few hundreds $$$ each, and pending on the envioroment you would need additional APs, Antennae etc., and probably will end spend thousands of $$$ on sensetive Wireless Hardware.
There are cable depending cameras, but that means laying cables from all the peripheral spots to your computer.
What the above means?
You need to get a professional person that would survey your property and evaluate what would be the most cost effective method to cover your specific envioroment.
:sun: