Okay, let's talk about saving money with stop bath, and we will use Kodak Indicator stop bath as the example, because it is essentially concentrated vinegar with an indicator added.
The Kodak bottle is 16 ounces, and if you dilute it as directed it makes 32 quarts of working solution.
Freestyle sells it for $6.99 US plus tax and shipping - lets say $8.00 US (assuming one buys it with other items).
I use two US quarts per printing session, although if it is dilutes as directed, two quarts will usually work fine for more than one session, if they aren't separated by more than a couple of days. That works out to $0.50 per printing session (or better).
Store vinegar is usually about 5% acetic acid, so you would normally dilute it 1 + 2 to get the acetic acid to the same concentration as the Kodak version.
If Ariston is paying $1.00 for a gallon of vinegar - which is about half what we pay up here, for the cheapest versions - than once that is diluted 1 + 2, he will end up at twelve quarts of working strength stop bath. If one uses two quarts per session, that works out to $0.16 per session - slightly less expensive that the stop bath.
But wait, there is more!


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My storage space for chemicals is at a premium. It is a lot easier for me to store one relatively tiny 16 ounce bottle than a gallon jug.
Why might you save even more if you use indicator stop bath vs. vinegar? Because you can reasonably rely on the indicator to assist you in maximizing your use. I would be much more likely to replace a vinegar based stop bath too early because it lacks an indicator.
And as for using water instead of stop bath:
1) if it isn't a running water bath (which would be difficult for me to establish in my darkroom) it is much less effective at stopping development promptly; and
2) if it isn't a running water bath (which would be difficult for me to establish in my darkroom), it will inevitably lead to there being much greater developer contamination of fixer. Fixer contaminated by developer is both less effective and has much less fixing capacity. Which leads to using more fixer, and fixer is more expensive than stop bath, which means one spends more money.