Depending on your airport transportation I would recommend stopping to purchase anything out of the "ordinary" at a major grocery chain. If you rent a car this is easy, if you are taking Mears consider switching to a towncar.
There are lots of great companies and most will allow a complimentary 1/2 hour grocery stop. Its usually just a few more $$ than mears and with the convenience of not stopping at other resorts and other terminals (on the return) in addition to the $$ savings in groceries it is worth it.
We stop at the grocery and pick up specialty items as well, my dd is milk allergic and drinks soy beverages. We also get cereal and fruit for breakfast, pb&j and bread as well as snacks, soda, juice and water. When you consider that a bottle of water at the parks will cost you $2.50 its worth it. We get a styrafoam cooler at the grocery and just fill with ice as needed.
If a grocery isn't an option perhaps a call to CS will get you a definate answer as to if they have it and if not the easiest way to get some.
TJ