It was $1.50 for the ice cream from that specialty case in the Windjammer. I am 99% sure that is where the OP's photo is from. Every other dessert in the Windjammer was free and there were soft serve cones available for free just a short walk outside on the pool deck as well.
For more ice cream options, Ben and Jerry's was available at a shop in the Promenade for I believe $3.50 (not sure exactly because I only briefly looked at the price list and didn't buy any) which doesn't seem excessive to me considering what Ben and Jerry's costs in any other store.
There was also ice cream available as an included dessert option every night in MDR.