Channel Plus #5445 coupled with their DA-550BID will do this for you. You can "create" four private TV channels, one for each camera input. These really work well for this application. Take a look here:

http://www.amazon.com/s/ref=bl_sr_e...cs&field-brandtextbin=Channel%20Plus

---Ed---

"But the guy at Home Depot said it would work."