I'm doing an experiment and I'll let you know how it works out when we've been at it for a while longer. Due to many reasons beyond my control, each person eats different foods than the other family members (I'd love it if we all sat down to the same food each meal--but that ain't happening), so we started a system for the kids like this:
Each child (12 & 14-years old) must make a weekly menu plan of Breakfast, Lunch, Dinner, two snack/day plus any treats, take out, Starbucks, etc. with each meal (B, L, D) consisting of at least one protein and one fresh fruit or vegetable. They are welcome to add whatever they want to the meals to add nutrition, variety, etc...
Each child gets a food budget of $80/week. This may seem high but we live in an expensive area and expect them to purchase organic, nitrate-free, preservative-free foods and it's no more than we spend per child anyway. Whatever they don't use for the week can be banked for future food purchases/birthday parties (not socked away for other uses).
I took each child (separately) to the grocery store we use most (TJ's!) and had them record prices per quantity of their favorite foods. For instance, a loaf of bread is $3.99 and has 12 slices. Then they added their foods and prices to a data base I'd already made of TJ's prices, so we now have prices for pretty much everything we buy there. This allows them to match their budgets to their menus prior to going to the store.
They make a shopping list for me, I pay for the items separately with their money and return the list with the receipt attached. I stick a color-coded label on the food before it goes into the pantry or refrigerator so there is no question as to what belongs to whom.
I'm hoping they'll learn all about nutrition, food preparation and budgeting through this experience. My main goal is to make them mindful of what they're eating.