I hadn't actually planned on addressing this, but after being asked "why doesn't Susan just buy a bunch of the less potent potions" by several people, it became apparent that people had clearly FORGOTTEN how shops in the games I'm parodying work, and how they'd restock only after waiting seven days in-game time, and sometimes you'd have to wait a bit longer than that, or travel elsewhere first, or do SOMETHING to get the restock to trigger, because video games are weird sometimes!
What do you mean an exorbitantly large percentage of this comic's readers have never played those games?
What do you mean I'm unfairly assuming readers are aware of logic that I, the storyteller, have neglected to share, and now expect them to accept without question?
What do you mean I definitely should have planned to have this strip before the one I originally had planned for today?
You say a lot of hurtful and critical things, imaginary person!
Anyway, it would take over 19 in-game years for Susan to get the equivalent of four of the more powerful potions.