It is really really expensive. I want to say it is about $10 after the deposit for the larger locker which is probably the size you will need for a cooler. The small lockers are really small. You have to go to the shop next to the locker and pay at the register. They will then give you the key. At the end of the day, if you bring back your key and receipt they will give you your deposit back, I think it was $5 or something like that.
We were switching resorts and had no car. I had a laptop that I wasn't comfortable letting them move so I used the locker for the morning at the park. I thought the price was a bit ridiculous.