One of the interesting aspects is how the mere existence of cheap drones will need to alter defence. Consider that for a terrorist group, once they've demonstrated the willingness to use drones, they can drastically increase the cost in defending against attacks by using very cheap fakes.

A government targeted with drones would not dare take the risk of finding out the "wrong way" whether or not the incoming drone is loaded with explosives, or is a cheap toy. Now imagine a steady stream of hundreds of cheap toys, with one every now and again loaded with explosives.

Say (just to pull random numbers) that a real "homemade" drone costs $10k/piece, and a fake one drops down to $100/piece and you can send out 101 w/one real for the cost of 2 real ones. Yet the cost of defending against the attack has gone up 100-fold.