Personal satisfaction from gardening - PRICELESS!
I think the value of a home garden is so much more than just the amount of money you save at the supermarket. You build relationships with neighbors (perhaps start a bartering system, trading veggies for meat or honey or other goods). If you are sensible with planting rotations and cover crops you improve your soil, creating a valuable resource for the future. You limit your carbon footprint. You can dedicate "wild" areas of your yard to provide habitat for wildlife which in turn will help pollinate and manage pests in your garden. You are enriching your environment while most commercial farms, even organic ones, are harming it. This is priceless.