Home Brew Solutions: cheaper ingredients?

[Seele]

I have been doing darkroom work since the 1970s and have used both packaged chemicals and home brews following the multitude of formulae published all over the place. Obviously I got my ingredients from chemical suppliers, both photographic, and for less common ones, specialist suppliers, and they tend to be high grade in terms of purity, often in AnalaR grade (≥ 99.0%), and if push came to shove, even purer lab grade.

Obviously you pay for the purity, and I never give it much thought. The other day I was going through my recipe notes and it came to me: if these recipes, formulated decades ago, were meant to be replicated by amateur enthusiasts of limited means, they would have made the allowances for using readily available ingredients rather than the high grade ones which should have been beyond the budget of the amateur, if they were even available to the public at the time.

Let's consider it from my perspective as a Sydney-based Australian. Sodium carbonate (anhydrous) from a photographic dealer goes for A$22 per 500g:
https://www.goldstreetstudios.com.au/product/sodium-carbonate/

But getting it from my local supermarket as a "commercial grade" product is A$5.25 per 1kg, a significant price difference of more than eight times even without shipping:
https://www.coles.com.au/product/lectric-washing-soda-powder-1kg-6560700

Correspondence with the manufacturer gave me the impression that it is approaching, if not reaching the AnalaR standard but they have to safeguard themselves by not claiming it to be "photographic grade", whatever that means.

Other examples include borax, sodium sulphite (as used for food processing like preparation of sausage casings) and many others.

I would welcome my fellow correspondents' thoughts, thank you.