Hi Mounis
Welcome to the forum,
We do understand that to anyone on the outside looking in the security forums do seem like places where diyers come to get flamed rather than gain information. The problem is, people come here with high expectations and no budget. This is because the internet is flooded with cheap CCTV which most professionals would not trust to prop a door let alone secure their property. When CCTV went digital 10 or so years ago the box shifting companies selling computers thought they add another string to their bow by selling DVR's and cameras. As a result there are many variations of cameras and digital recorders out there, some are very good but unfortunately most are very poor. It is a case of you do get exactly what you pay for with CCTV no more no less, the price is a very good indicator to the quality in most cases. So when posters are told what they dont want to here they accuse us of flaming when really we are telling them as it is.
First off you need to decide the purpose of the CCTV system, once you know the purpose then you specify the system to the purpose. Any deviation from the purpose makes the system pointless. For example if the problem is that your car or shed is being broken into (or you are just worried that it might be) you will need cameras that will identify the person doing it. Otherwise whats the point? If your shed is broken into and the CCTV system does not identify who did it then the CCTV is only telling you what you already know. If you are only using the CCTV as a deterrent then dummy cameras is the cheapest solution.
I could give hundreds examples of purpose, it would be much easier if you just tell us your thoughts on the purpose of your CCTV. We will then give you ideas on what we think you should use. If its outside your budget then my advise would be save up or dont bother. The cheap stuff is exactly that