The US pharmaceutical marketplace operates under a "free pricing" system. Companies are free to set their price to whatever they feel like. The only thing that limits the price is the response of the market.

I agree that it's a not a price vs. demand equation since demand won't drop off for a product like this since there aren't really any substitutes (other than the vial and syringe which has limitations). However, public response to a price is a very strong motivator for drug companies. I can guarantee you that Mylan's C-suite is in a frenzy right now trying to figure out how to fix this.