Since the cans and/or cases aren't opened, I would try to return it to where you bought it. They may not give you cash, but a credit for other items.
Your pediatrician office might let you put something on the bulletin board about it. You'd have to ask. Money is so tight right now for so many people. Your pediatrician might know of someone else who could use the formula but $80 per case could be a stretch for some people all at once.
You can see if there are any takers locally on Craig's list so you don't have to pay for shipping.
I worse come to worse, you can always donate it. Many places will give you a receipt for the price you mention and you can write if off as a charitable donation.
I hope you find someone to buy it.
I would advise not buying so much at a time next time to make sure your daughter likes it and isn't switched to something else soon.
Good luck and best wishes!