Bacon. awesome. My top pick.
Also, the veggie of choice is peas - or any veggie mix that has a lot of peas in it.
There is something satisfying about adding Spam - intensifies the artificial foodness, I think. Better than hot dogs, but hot dogs are really cheap.
Another good combo is baked beans. Sounds strange, but try it. Yummy, cheap, filling.
Also, you can make the stuff, add an egg and some evaporated milk, stir, top it with bread crumbs and bake it.
Also, if you're sick of kraft mac/cheese, boil up some spaghetti and put the butter/cheese/cream on it instead - good change of pace, also cheap. Use the macaroni in something else, it's REALLY good quality.
Oh, the absolutely best way to make it is to add butter, let it melt, add cheese, let it start to melt, put a tiny bit of cream or half-and-half on it, mix.