Not to over-analyze a comic, but the business model might not be awful in this case. They sell all potions for 20gp kind of like the original dollar stores. The

Not to over-analyze a comic, but the business model might not be awful in this case. They sell all potions for 20gp kind of like the original dollar stores. The one particular item is at a loss, but the majority may be at a profit or at least the aggregate based on volume is a profit. Basically they have loss-leaders to get people to use them as their only store.