we normally get room service for breakfast & go all out for dinner with our appetites delight, but some of our fav cheap eats & snacks at wdw are..
magic kingdom - ditto on pecos bills we share a hot dog or burger for a snack & they have a big fixins bar, main street bake shop for dessert goodies.
epcot - ditto for the lotus blossom cafe at china, we get the orange chix (similiar to sweetnsour chicken) and ditto for the tangerine cafe at morocco we share the couscous & baklava for a snack. we also like cantina san angel in mexico on the lagoon tacos & margaritas.
mgm studios - toy story pizza planet we share a pizza for a snack, min & bills dockside diner we get a chocolate malt.
animal kingdom - chakrandi chicken shop in asia the chicken in peanut sauce & noodle bowls. or flame tree barbecue.
downtown disney - wolfgang puck express good soups & sandwiches, ghiradelli soda fountain & chocolate shop, umm, we share a sundae here every trip & always buy some of their delicious chocolate for home.
alot of the wdw resorts also have great inexpensive places to eat, like the boardwalk vendors like crepes on a stick or the takeout window at spoodles. or fort wilderness' trails end restaurant which has a variety of food offerings for a good price, including an all you can eat breakfast buffet.