if you havea local
maplin , go take a look at the cctv deals that they have.
i picked up a 2 camera one at a bargain price., 2 more cameras can be added to it.
spy cameras generally give quite a poor image, look for something with plenty of tv lines.
A pc cam is a good idea , providing they dont nick your pc.
My first camera was a wireless one, cost me 30 quid, it works ok.
Now i have fitted it to my wired cystem that has motion detection, every bit of interference triggers the motion detection.
The wireless camera came with no way of storing the video, i just connected it up to a video recorder.
Worked a treat but took an age to look through the recordings.
the new cystem is the nuts, should anything be caught on camera i can record it to a flash drive and pass that on to mr policeman.
It wil also send a smart phone any motion detected images.
I dont bother with that as it can be quite sensitive, pics of my cat in the garden are of no use
cctv images will get the police to actually come se you should something happen.
Bar that they normally just give you a crime no.