Serving size: 1/2 cup cooked

Cost per serving size: 10 cents

Calories: About 100

With about 7 grams of protein per serving, you can sub beans for meat in many recipes. And they've got plenty of fiber, folate, potassium, and magnesium. To cook dry beans, soak them overnight, or boil them for a couple of minutes and let them sit off the heat for an hour before cooking. If you use canned ones, drain and rinse them first to cut down on salt.