I was recently involved in a food-value debate with a friend. He contended that his two frozen burritos for $0.35 each made for an unbeatable $0.70 lunch.
This is only true if the only factors in the game are calories/dollar. And I would win strictly by carrying around a bottle of the cheapest olive oil I could find.
All food is not created equal. Even if cost is your primary concern when choosing a meal, you need to think past the hyper-short-term. After all, you wouldn't put low-grade fuel in a Lexus, would you? Because fixing a ruined car costs a lot more than what you're saving now eating chemical-laden garbage your body doesn't even recognize as food.