Oh yeah I realized that it was Redundant ages ago. It works in any case. The idea of leaving an option for a string for every potion is a good one, Thanks! Have you found it easy to set up and work with otherwise? Is it working well?
Edit: I did recently find a bug related to attempting to buy a potion without an empty bottle and when your wallet is full. As written, the rupees are not properly returned to Link due to the wallet being full. What happens is the script gives the rupees immediately, before they drain in the normal fashion. To fix this, I added a line to temporarily increase the wallet cap by the amount of the rupees being returned. Then, on the screen just outside the shop, I drop in a simple ffc script that resets the wallet cap to where it should be. It works well on my quest, and so far I haven't had an instance where the wallet has more rupees than the wallet capacity.