Wow! That's a lot of $$$. Our insurance is tiered for prescriptions and we pay a $40. co-pay for each of the epi pens in our family (a regular one for my older ds and an epi jr. for my youngest). The $40. is the highest of the tiered amts.
One thing I do to keep the costs down: check with a pharmacy or two and find out what the expiration date is on their epi-pens. One time I was about to get one filled and it would have expired only 6 months later so now I always ask first. The manufacturer prints the exp. date on the packaging itself and it may differ from the one the pharmacy slaps on with their label. The best I've gotten is 18 months out, pehaps longer (can't remember exactly). But there was a huge difference between a couple of different pharmacies. If I had to pay the whole thing out of pocket I'd be shopping the price around as well.