OK, so this was my quest last night. First I tried Ale & Compass Marketplace, no surprise, only single bottles. Then the Solarium temporary Marketplace at BC, no luck at that time (Surprised by that). Found some at the Screen Door on the Boardwalk. It was a pack of 8 small bottles. After one day I have three left, so headed back to the Screen Door on my way back from Epcot. That is the closest to a “case” I could find. I think you can get a regular case at the Speedway gas station which is walking distance from the Boardwalk.
I will note that I was also looking for half-and-half, and saw none in the case at Screen Door. The CM there asked what I was looking for, and said that they were keeping some things in the back for now. He did have half and half but he had to fetch it. So if you don’t see something in the case, don’t be afraid to ask.