Have you seen people doing drone racing? I think this would be pretty easy for them, and even if it's not reliable you're out $200 and some DIY time. Even if it takes 5 attempts, $1000 is cheap as hell to assassinate someone
It takes very large amounts of money, skill and time to develop and run an intelligence network capable of pulling something like this off.
As counter intuitive as it seems these organizations are extremely risk averse because to them risks means years of work down the drain, opportunities lost and often for good and quite likely dead assets and or agents.
A $200 or even a $2000 drone doesn’t minimizes these risks it introduces additional ones.
Killing someone in a hail of bullets is easy and reliable, using a toy with a small explosive attached to it isn’t.
Disclaimer: all hypotheticals, I don't advocate violence, I would never do this even for hypothetical purposes
Small drones can’t cary a lot of payload getting your hands on high explosives that would actually do enough damage isn’t easy, rigging this up in a safe manner isn’t as easy as you think either.
Like I’m not saying you should try to do this to prove a point but you have much higher chances of blowing yourself up or even more likely be arrested prior than you think.
Have backup gunman to mop up if needed, likely same pointing illuminator at target.
Not what happened but easy enough.
Might as well call a B-52 to carpet bomb the place.
You aren’t getting an airship and a few dozens of drones into a country like Iran.