We just got back from AKL. DS is 14 months old so we did the milk thing too. I brought milk - the kind that can stay at room temp - they look like little juice boxes.
When we ran out of those I bought milk at the Mara & the gift shop. They were the very small cartons & cost $1.35 a carton!! (I am going through my receips as I type).
As DISMOMof3 said, if you are renting the town car from the airport to hotel (we used Tiffany Town Car), take advantage of the stop at the grovery store. We did & bought bottled water, diapers, snacks, etc.