Hi,
We stayed at the Caribbean Beach Resort a few years ago and I bought milk in the souvenior store there by the food court.
I do not remember the name of the store but I am sure someone else can help. The souvenior store also sold donuts, etc. for less than what you had to pay in the Quick Mart ( a part of the food court).
I had some trouble finding places in the parks to buy milk for my DD.
I just wish Disney would offer small individual jugs of milk in the snack carts and all the restaurants in the parks. Time and time again, I could not find milk in the parks without having to track way out of our way.

You would think, since it is a healthy choice, and with all the small children at the parks, Disney would sell it in the restaurants.
Oops! Sorry for the rant.