you can get fairly good quality CCTV camera's from alot of places now days at a cheap price ie £100+ however it depends on what you need it for, as a deterant or for evidence.some cheap camera's are ok for watching on a monitor live. but forget it f you want to record images. & as for evidence courts wont accept them.i use a Colour CCTV Camera dome & DVR unit that records high Quality live time footage for only £350 & that has been accepted as evidence. try shopping around.Dont forget if its for a business its tax deductabletry some of these links for a start
www.maplin.co.uk