And then defense contractors will sell it to the government for a 10,000% markup.

But in all reality they would steal it after the inventor commits suicide with 2 rounds to the back of the head

“actually cheap” and “reliable interceptor”, the US military industrial complex

This is antithetical to the US military industrial contractor complex doctrine.

I've sometimes thought that WW2 flak cannons (~artillery) with a programmable fuse (set immediately before "launch" by radar) could be effective. You would get longer range than C-RAM or laser and artillery shells are cheap. Shahed/Gerans are not particularly fast or durable. It wouldn't take much to make it fall out of the sky: close enough is good enough.