You're single handedly discovering of the game's exploits xD
But yeah, when I first priced the herbs (which you can also buy in Mappi Village), I thought about making them a super inconvenient way of grinding Coppers. But yeah, maybe I should increase the price at least so you gain at most 1 Copper per herb idk...
As for Lianna's teacher, I always use uppercase M when she refers to him. I wonder if it'd make more sense to restrict that to Lianna's lines only tho, and go lowercase when someone else (or even a narrator) says it.