This site provides a seven-day menu, shopping list, prep-in-advance instructions, nutrition information and even recipes. Granted the prices quoted are from 2006, so it may be up a bit from there. But still ... darn cheap ... especially considering even a basic stock of food in your house will likely contribute some of the basic ingredients for these menus.
And (Lisa will love this), the menus are very low on meat (meat is expensive), but still high on protein.
For example, this is Monday's menu:
Breakfast: Pancakes, syrup, orange juice, milk, hot tea
Lunch: Lentil & Vegetable soup with dumplings, milk
Dinner: Pinto beans, onions, hoecakes, collard greens, iced tea
Snacks: Cinnamon toast, milk for children, tea for adults
Nutrition: 1656 Calories; 33g Fat (17.5% calories from fat); 71g Protein; 275g Carbohydrate; 42g Dietary Fiber; 54mg Cholesterol; 3312mg Sodium
Not too shabby. Now, I'm not convinced my kids (or my husband) will be all that thrilled with pinto beans, onions and collard greens for dinner. But, it would likely be filling and certainly nutritious.