I just went to Radio Shack, and got a tiny little black and white security camera (it was advertised to check and see who's knocking at your front door), and a little video monitor (10 inch or so). Ran the camera into the Video In of the T.V. It even has sound (the camera has a mic in it). Just get two, one for each direction, and you're ready to go. It was not expensive at all.