The tooling and electronics for one drone model is amortized across millions of consumer drones, and also shared with other consumer electronics.
The tooling for an artillery shell is used only for artillery shells. Not many consumers looking to buy 152mm shell casings and high explosives.
In the industrial age, volume production is the usual solution to keeping costs low. Artillery shells would be a lot cheaper if we built as many of them as we did in WW2.
(As a side note, this is one reason why housing was so cheap in the post-WW2 1950-1970 era. There was a whole lot of surplus construction equipment leftover from WW2, so you could acquire the tooling needed to build a subdivision really cheaply. Once the surplus aged out and there was no economic reason to build a huge number of new diggers and bulldozers, construction got a lot more expensive.)
What you're actually asking is "Would artillery shells be cheaper if we could offshore all the actual work to cast, machine, and fill an artillery shell to China and then just ship the end result over by boat?"
And the answer is yes, China makes their artillery shells cheaper. American labor is very expensive and American military manufacturers tend towards low volume nowadays, because they don't trust the government to commit to 1 million shells a year for two decades, because every time there's a changing of the guard in the whitehouse, plans get gutted seemingly as a "Fuck you" to anyone who worked with the previous admin.
That being said, I'd like to see a citation for the $3k figure being thrown around. The number I've seen is more like $800
"the U.S. currently pays $3,000 for its most modern shells, according to an Army spokesperson. That price includes the charge, fuze, and shell body." [1]
The drone weighs a few hundred grams and carries nothing. The moment you look at anything close to a carrying capacity of 50kg, you are well beyond the $20k range.
