I still have an old 900Mhz A/V sender that I got from a discount store many years ago. It would work, but there were so many other devices using the 900Mhz range (an older wireless phone, some RF controlled toys, etc..) that I always got irritated by the interference. It's range wasn't much, especially if there was more that one wall or a floor between sender and receiver.

My 2.4G A/V devices don't seem to care about walls or floors, and produce a nice sharp picture when there is no interference. I have yet to find the limit to their range. They work easily from corner to corner of my fairly large house.

Dave