In the Atlanta area, the Kosher Coke (as we called it) was not much more expensive. If regular 2 liters were $1.09 I think the store had the sugar stuff for $1.29.
If I remember, the caps were red or yellow and had "OPU" on the plastic bottle. After Passover they took the extra and just put them on the shelf with the "other" stuff.
I would go on scavenger hunts and take 5 or 6 from each store, leaving some ofn the shelf for our Jewish friends
Too bad Coke didn't make "Classic" Coke with sugar. I'd have paid more for it.
You can REALLY taste the difference.