The Hess station near the EPCOT resorts has milk, snacks and stuff.
Any of the Deluxe Hotels that have DVC has groceries in their gift shop (expensive).
If you are staying at Animal Kingdom Lodge, when exiting the gate take the first right on Sherberth and take it to Irlo Bronson Hwy (about 3 minutes, can't miss it Sherberth winds a little and then you see the lights from Irlo Bronson) there's Publix and Super Target down on the right of it.
However, my motto is Pack Less Clothes, Pack More Snacks and Dry Goods!