Between the FDA and patent lawsuits, good luck doing this in the US. Several major drug companies have already failed miserably and Adrenaclick isn't anywhere near the huge success you apparently think it would be.
So are you saying it is not possible to provide an epipen equivalent at lesser price than mylan? Then what wrong are they doing again? It is literally not possible to sell the product at a lower price.
Well, Adrenaclick does exist and is cheaper, but I'll assume you meant "very hard" rather than "not possible".
It's hard because the US pharmaceuticals market is broken, something that Mylan is paying money to encourage now that they're on top. Have you read the post I linked to?