Well, there are at least two questionable assumptions here. The first being that the market is the perfect (or at least the best) mechanism for regulating access to potentially life-saving drugs such as these, but doesn't take account of the fact that a number of people may unnecessarily die before the market reaches equilibrium. There are human beings involved here, not just abstract concepts of supply and demand.
The second is that there isn't a viable or acceptable alternative, and I would argue that the UK has one in the National Health Service, which is essentially free at the point of delivery, regardless of the actual cost of treatment. Of course, that does require much more intervention in the "market" than many free-market countries would contemplate, and ultimately is as much a political as well as an economic choice (if not more). And of course it comes at a cost, in that taxes are higher than they would otherwise be.
I don't want to start a political discussion here, as that would be against the TOU: I just wanted to highlight that I don't think you can reduce an argument about access to life-saving drugs to questions of mere dollars and cents.
We don't have to wait for the market to get to equilibrium. It's already there. There are at least two viable alternatives to Epipen - Adenaclick (certainly the better alternative) and a basic syringe. Both are available immediately and both cost less.