Lentil Soup

Lentil Soup feeds six for about $5—that's less than a single Starbucks latte, and it is the cheapest on this list by 20%. A pound of dried lentils ($1.50) provides 13 servings of protein, with red lentils dissolving into a creamy base in 20 minutes (no soaking). Add an onion, carrots, celery, canned tomatoes, cumin, and a bay leaf. Nutritionists would champion this soup for its fiber and iron content, while the cost per serving of $0.83 undercuts all rivals.