If your budget-airline-flight home will be hours long and you haven't pre-ordered an inflight meal, don't spend every last cent of your local currency before you enter the pre-departure area of the airport. Leave some to buy a snack or a boxed meal so you will have something to eat on your plane ride home...that's if the airline allows you to eat "outside" food (food not bought inflight). If your airline does not allow "outside" food, then you'll have some money to buy an expensive piece of snack or meal on the plane.
Before my night flight from Busan to Cebu, I made sure to buy a boxed meal from the convenience store at the pre-departure area of Gimhae International Airport. During the flight, when it was time for dinner, I whipped out my boxed meal and smacked my lips. My friend who was sitting beside me laughed when she saw the guy across the aisle eyeing my meal and hungrily holding his stomach.