I think the one thing no one really mentions is the fact that drones are extremely easy to build in the comfort of your living room. If you have a 3d printer, some spare parts laying around and a cheap electronics store around the corner(check, check and check in my case), you can build a drone for less than 300 bucks which is far less than the retail ones - completely autonomous, no radio link needed, takes off, does what it does and lands on it's own with no human intervention.