I've actually messed around with putting a camera on a helicopter,back when I worked for radio shack. It's actually not that hard but it's going to cost you around $400. We had a small wireless camera (which we powered with button cells), A ~$100 R/C helicopter and a video baby monitor.
Just for fun I Googled up some similar products which could work. (not saying it will be perfect)
This could be interesting for capture the flag games
With these two items you could have real time video with a range of ~25m. Keep in mind most of your money goes up in smoke if someone lights them up or you crash.