Consider growing a lot of your supplementary foods in your own garden. Things like cherry tomatoes, lettuce, herbs, silverbeet, chinese greens, varieties of peas and beans grow almost anywhere and in almost anything. This way you save money for some of the more essential organic foods that you can't easily grow at home.
There are many, many discussions on this forum about going organic, about growing vegetables, about sourcing organic produce, about buying co-operatively. Just shout out and mods/admin and membership will be there to help you.

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