I used to dabble in model aircraft. A 'drone' is just a computerized one. I could regularly cobble one together for a few hundred, most of that being electronics. The body was balsa wood with shrink film covering, super cheap. Not everything has to be titanium and carbon fiber. Nowdays, the electronics are cheaper than ever, and can be strapped to many homebuilt craft with little issue. This all ignores vto style crafts, which I am unaware of. The hard part is training your control system, but once calibrated decently you are good to go.

The problem is the bar of effort. Bombs are even easier to build, yet few with the will to build one for nefarious purposes seems to be effective in doing so, even with provided materials (without training, see IEDs). Same with guns, tanks and other complex items. Anyone can make a gun from hardware store items, but most criminals will steal one instead. The impulsive instinct that drives most crime seems a burden on complex tasks.

I'm not much of a chemist, but I don't think bombs are particularly easy to build. I do a bit of metal plate etching, and I've found multiple times that useful chemicals (specifically nitric acid and hydrogen peroxide) are pretty tricky to get hold of, because assholes use them to make bombs.

I had a friend who was making black powder as a schoolkid, and he actually had the police turning up at his house to ask questions about his purchasing history - which is a small sample, but it fits with the basic intuition about how you'd stop people from building bombs: make non-household bomb-making stuff impossible to get hold as a private individual, then just monitor people that make weird purchases of the chemicals that remain.

Yes it is. For about 150 you get an empty airframe. 200 for batteries. 200 for all electronics (flight controller, GPS, receivers etc) . 100 for servos. 100 for wires, connectors etc. 200 for motors and esc. You need a radio sender and a laptop as well. I have build many long range uav's. Compared to 10 years ago the landscape changed a lot.

That sounds fascinating. What sort of control/GIS software do you use on your laptop? Where would you recommend someone interested in this research to get started?

Stm32 flight controllers f3 or f7 with inav on it will do great. Ardupilot can be flashed on most as well. For about 40 you have one. Nice hobby I would say :) check long range fpv on YouTube

Absolutely, flying wings are very efficient and can carry a good amount of batteries. Just on 700mhz video you can go 30+ miles away with full control. If automated much farther.