There's no difference if someone's charging alot or not much for that potion. The point is that it's definately not good to charge money for such substance, it's plain wrong. So if one charges 100 or 1000 doesn't really make a difference.

If one does charge only for the accomodation and food etc., that's totally fine IMO, but charging for the substance is not different from drug dealing and disrespecting the sacred drink.