I did qualify multiple times that there are costs associated with engineering, So I feel that it it's implied that the 4000x figure is a naive one.

I'm sure labor is involved, and maybe it's a lot, but it still seems like an awful lot of money for a piece of plastic.

Even if the actual specialist labor had been minimal, there's also the amount of time and effort it takes to accumulate enough knowledge to become a specialist. It's like the joke about spending $200 for a repair guy to come kick your printer in just the right spot to fix a print jam--you pay him $50 for kicking it, and $150 for knowing where to kick it :)

Yes, they will charge a similar amount for producing another guard from an existing scan - I’ve had that done. It was also completely unnecessary in my case, it’s clearly an easy money grab for some offices.