I sell and install security camera systems. Do yourself a favor and stay away from wireless. They still need a cable run to them for power but the video signal is wireless. They don't have a very good range and lots of interference issue. For $1000 you can get a nice 4 camera IP system that will connect to your existing internet, at no additional cost, and can be viewed from any computer or phone. Make sure to get an IP system. The picture quality is at a minimum 3 times better with IP over the old analog systems. They are easy to install yourself. Plug and play with just minimal router port forwarding knowledge.
This is what I am planning on doing this spring/summer install a few IP camera's around the hosue then, get simpli safe for the doors and monitoring. Simpli safe is relativity cheap compared to the other brands, although I haven't read or looked up many reviews on them.