[himinlomax]

Flying it via camera is very limiting, you have to be close enough.

However it's quite possible and indeed not that hard to build a long range, autonomous RC plane. You just need to use the sensors typically found in any smartphone: GPS, camera (for ground imaging), accelerometer, magnetometer and so on, add inexpensive barometers and ultrasound or optical sensors for altitude, and mix all that up with the proper algorithms to end up with really accurate positioning. In fact you can even have accurate positioning when losing GPS.

If you're not concerned about speed, a simple and cheap powered model sailplane made of styrofoam could easily be made to fly for hours on battery. Cost: a few hundred dollars worth of parts.