There are dozens of different HD cameras you can put on an RC plane, multirotor or helicopter these days but if you're looking for something small, light and cheap then it's hard to go past the keychain cameras and the #16 is one of the best I've tested so far.
I will post some better video (from a sunny day) later but this video will show you what you get for your $40 and how the camera performs as a recording camera and also as an FPV camera.
Pro's:
- lightweight and small
- tough
- cheap
- surprisingly good recorded video quality
- no measurable RF noise output
- firmware updates available
Con's:
- live-video output not really very good for FPV
- only 720P resolution at 30fps
The eBay vendor I bought mine from is eletoponline365
More information can be found on RCGroups