Baked Potato Bar

A 5-pound bag of russet potatoes costs $3. That's your entire entree for four people. Bake them at 400°F for an hour (or microwave for 10 minutes if you're impatient), split them open, and set out toppings: butter, sour cream, shredded cheese, canned chili, broccoli, bacon bits. Total with toppings: about $8. Kids love it because they get to build their own. Adults love it because it's secretly a complete meal. The potato does all the heavy lifting — you just show up with condiments.