Take two pounds of off-brand velveeta (that processed "cheese" stuff), a half-pound of browned ground beef, and several sauce packets stolen from Taco Bell (or similar hot sauce/salsa). Mix all that together, heat it all together, and stir often. Eat with tortilla chips.
All together, it's between $8 and $12 depending on how often you've walked out of Taco Bell with pockets full of sauce, and it can be as many as six or so meals (though I recommend making it by the bowl and not the pot so it doesn't go nasty sitting in a fridge).
Also, Totino's $1.25 frozen pizzas. Things about the size of a dinner plate and thin as paper, but you can cook them in the microwave and turn them into a burrito or something similar. Good in a hurry.