They’re buying four trash cans at a time via a process that can take months of paperwork by the contractor. It’s simply not designed for such low volume scenarios.

It’s a bit like doing a custom PCB design and fabrication run for personal reasons. It’ll be $10 worth of components, but a half dozen might cost you $1k if you want someone else to set up a run on their machines to make ‘em.

The Stinger missile example further down seems more egregious. edit: Maybe less egregious than I thought; its original microprocessor is now obselete. https://en.wikipedia.org/wiki/FIM-92_Stinger#Replacement