It's getting to be canning supply clearance time at some retailers. Keep you eyes peeled.
Even if you don't can, there is a special bargain on Vitamin C in the canning supplies. Ball brand Fruit Fresh is a little dextrose and a lot of Vitamin C. Each quarter teaspoon provides 230% of the RDA, and there are 141 servings per 5 ounce container. Not sure how this compares with your vitamin C source, but when on sale near summer's end it may be a preparedness storage solution for you.
Another useful supply item is pectin. Remember Kaopectate? Yup, clay and pectin are the main ingredients. If you read the labels carefully, you can find both liquid and powdered pectin with minimal other ingredients. If you buy in the stores, look for the 4 ounce or larger jars of dry pectin, not the boxes with a lot of packaging and a couple tablespoons of product. We also keep the liquid pectin for canning and home remedy use. It's already hydrated and smooth for adding to jam fixings or a bowl of oatmeal.
Note: I am not a medical professional. I make no claim that pectin or vitamin C are good for you or will benefit your health. Do your own research on the usefulness of these substances and make your own decisions. Sheesh.