If you have a large food garden then, there are cost savings to be made by buying consumables such as pesticides in larger quantities. An example of this can the found with the natural insecticide Pyrethrum. This page is a simple cost comparison of two different size containers of Pyrethrum commonly available in the market.
Comparison between Kendon 1 litre and Yates 200 ml pyrethrum concentrate. Prices as of March 2021 (Australia).
LEFT: Yates 200ml Pyrethrum. It is readily available at nurseries and hardware stores. RIGHT: Kendon 1 Litre Pyrethrum. While not as widely available you should be able to find this product (or something of a similar size) at stock and station agent stores.