Kraft Mac and Cheese (I prefer ones in cartoon character shapes, as it's chewier.) and a half-pound of cut up hot dogs. Add some tabasco sauce, and it's a super cheap and tasty meal. Terribly unhealthy though. Less than $2 for the whole thing, if you get cheap hot dogs from Walmart. (And assuming that you already have milk, butter and tabasco sauce.)
It's much nicer with better hot dogs of course, but this is about being cheap!