It's not difficult at all. Cheese, butter, and eggs are all cheap. Hell, if you're not a stickler for local and pastured meat, that's quite cheap as well (though you can usually manage to find decently-priced sources of those -- especially if you find a group to cowpool with.)

My standard meal is eggs, sausage, and onions sauteed in butter and topped with salsa. Very cheap and fast (and good).