Dried beans are super cheap. If you want to season it with pork, you can do that cheaply too. Overall, grocery prices in Chicago are expensive, so I watch sales and stock up. The cheapest bread I've found is a brand at Dominicks (Safeway) called Nancy Martin. It's 85 cents or so. Hamburger and hotdog buns are always on sale. Eggs are usually on sale, too, and can provide protein. Tortillas - I love corn tortillas and my favorite brand is 33 cents/pkg everywhere.
I've recently learned to make Pakistani food from a friend. He makes a dish that is typically for breakfast, but it is something I make at night. Simmer a can of chickpeas (rinse/drain), some potatoes, peppers (we use serrano), chili powder, tumeric, and water. Top with cilantro if you want. Make paratha dough with flour, water, and some salt. Knead the dough, and then break off pieces, roll them out with a little flour. Fry the dough in a pan with some oil until you have something resembling a flour tortilla. Filling, cheap, and delicious.
The world's smartest people over at the DUmp can't figure out to live on a budget. Shocking...