Having a convenience shop in the airport is a necessity. I realize that most people complain about the prices, but shouldn't they have thought about it before coming to the airport? Sure you cannot bring liquids in the airport, but last time I checked you get free non-alcoholic beverages on your flight. If you're not smart enough to think of your convenience needs before coming to the airport, then you will have to pay extra for the privilege. These place exist because, customers keep coming back.