If you want to enjoy a vacation at Disney world and you’re on a very limited budget your best bet is to drive to the Walmart outside of Kissimmee (otherwise the prices are asinine) and purchase some decent quality lunch meat, bread, snacks and drinks. Kool aid packets are easy, and make the fountain water taste better. Bring the stuff back to your hotel and store it in the fridge in your room.
You can eat breakfast at the hotel, grab an extra piece of fruit for snacking on your way out of the breakfast buffet and then eat tailgate style in the parking lot or take a break in the afternoon, sit by the pool and have a picnic lunch.
Check the local coupon books for places to eat, like chilis all you can eat soup and salad for $7 or 8 bucks.
While you’re in the park, many of the overpriced treats can be split, like the giant churros for $4, the warm gooey cinnamon buns at the Fantasyland tavern, etc.