X10 are inexpensive and work very well .. you can have several cameras, that come with a switcher (swich from one camera to the next) iether pre programed or with a remote control .. you can stream it .. so that you can view the cameras from home too .. in a 4 way split screen, kind of
check out this link for the best deals
http://www.x10.com/products4/google/homepage_cam.htm