You've described the problem:

> here is no “price” for a drug

Yes, there is. If we look on their 10-K statements, they will have a fixed cost and a variable cost assigned to each drug. The variable cost will be just the manufacturing, and the fixed will be research and overhead allocated to this drug.

Total cost = fixed + variable. The rest is profit. We can decide what a "reasonable" profit is, and Total Cost + Profit is the notional "price."

That doesn't mean treating them like a state monopoly and the final price is fixed by law, but it does tell us a "price." All those things you mentioned (list, net, Medicaid, AMP, ASP) are kinda irrelevant.