This blog post can be subtitled "The Fallacy of Cheap Fast Food." The below graphic illustrates how fast food really isn't cheaper than healthy food. It's much more expensive than putting together a simple home cooked meal. And in the long run, since fast food meals are high in calories and fat, they contributed to a wide variety of serious chronic illnesses which come with a high price tag.
I'm not sure how correct these prices are but I do know that frozen vegetables, dried beans, and grains are a great value and are much healthier than fast food.