BananaHobby sells the SR-71 with twin ducted fans (most powerful and easiest to fly option) for $299 currently. Arduino based control of servos will give you AI controlling of your RC plane and allow you take trigger stuff.

Check out the Arduino forum. They are helpful and a few have autonomous planes as projects. One is doing huge flights (for RC planes) across Canada one is doing it for aerial photography (photo events are triggered by GPS co-ords).