best grocery store i ever went to was when i brifly lived in bc. save on foods. they had a make-your-own-pop area at the back of the store. you paid for the empty plastic bottle and put whatever you wanted into it. the wall had many dozens of flavors, all numbered, and you could consult a chart to add the correct number of squirts of each syrop to achieve whatever they suggested. or make your own. then put the bottle in the soda dispenser and it would fill. cap it and go.
Canada