We finally got cameras. We have been looking for a while. So many choices! Such a price range! We got a Uniden at sams club for $259.00. Wireless with range to 500 feet (we tested it up to 300 feet) It comes with 3 cameras and can add another. It has a small moniter with sound and great pictures. one camera is battery operated so we have used it in the trailer. Works great. (We had to buy the adapter for the cigarette lighter at radio shack for that) Says the charge will last 4 hours. The trailer rides were 2 hours, so it was great. We brought the charger just in case. It can also be hooked to the computer for a larger picture. We haven't tried that yet. Our barns have metal roofs and we have no problem. To buy the 4th camera would be $100.00. There might be some interference if you have too many things in the way of your signal, such as horse trailers campers and or vehicles.