So a "used" epi-pen's internal syringe might contain 4-5x more epinephrine than actually goes into a standard dose? I assume this means most of the expense of making it comes from the housing/mechanics. (And recouping whatever cost of QA/approvals.)
I haven't worked with this class of medical device, but I expect the major cost of the unit is in the approvals and lawsuits.
So far as the pen itself - They've got some injection-molded plastic, where the mold costs are amortized across the production lifetime. A needle + syringe, which are probably subcontracted from Becton Dickinson. A spring. A printed label. And the medication itself (probably the #2 cost).
The assembly of the above all had to conform to the FDA's Good Manufacturing Practices rules. Every part & ingredient had to have trace-ability to their source. With documentation thereof.
When we got our device approved (in a looser classification than this) we had to get UL approval ($50k per test, per device, per test-run), and we had 3 people on staff whose sole purpose was navigating the FDA paperwork and their approval process. I never heard what that cost was, but it was substantial. And then we had an IP attorney, and corporate defense attorneys to respond to the inevitable lawsuits.
The drug itself is very cheap. With an Rx you can purchase an ampule with about 3 doses for < $10.[1] You can administer it with an insulin syringe, which I don't think requires an Rx. Of course administration is a lot more tedious and requires some training.
I worked at a summer camp where we would carry 1 or 2 pens plus a bunch of ampules if we were in a wilderness situation where we couldn't get to emergency care and needed more than one dose.
The drug is cheap...because it's unpatentable (as a molecule anyway) and is old enough that any patents would be expired anyway.
The marketing of autoinjectors has some legitimate public health value, but it's also a clear business strategy to get new drug prices for an ancient drug
