Inevitably, players will sooner or later inquire about purchasing or selling magic items in the safety of town. A lot of common advice dictates to leave such discoveries to adventuring, and ban mercantile activities of this sort. Otherwise, why risk the dungeoneering?
These are just random my notes for OSE (or your B/X scoop or choice). Giving my inability to grok the game at first, and doing a cursory reading of the text I landed on something that wasn't obvious to me from the beginning.
Enter the Alchemist
An alchemist costs 1000gp/month in wages and they bring the following to the table if hired:
Recreating potions: Based on a sample or recipe, an alchemist can produce a potion at twice the normal speed and for half the normal cost (see Magical Research).
Researching potions: An alchemist may also research new potions, but this takes twice as long and costs twice as much as normal.
A potion of healing is nothing more than a 1st level clerical Cure Light Wounds spell. And the magical research estimates the cost to make them a week of labor and 500gp/level in costs by a Cleric of 2nd level or higher. Assuming they have the recipe, the Cleric is no longer needed.
N: number of weeks in a month
Potion of healing Price = (N * 500 + 1000) / (N * 2)
This yields 2 potions available per week, and no Cleric PC has to assist (this is my reading).
Alchemists, I would reckon, are rare enough in most settings to be only present in larger towns and cities.
So, turns out that, as in many open games and the overused Gygax-attributed credo goes, a calendar is important for potions. The alchemist specialty gives wages in gp per month. But magical research is on a per week basis. How many weeks are a month in this world?
Only with that answer we can get the price of healing potions.
With an alchemist:
Simplifying a month having 4 weeks -> 375gp/potion, 2 available per week
Simplifying a month having 5 weeks -> 350gp/potion, 2 available per week
Without an alchemist:
Regardless of how many weeks are in a month -> 500gp/potion, 1 potion available per week (per PC Cleric actively working on it)
This is of course an abstraction, but an interesting guideline nonetheless. More than one alchemist could be hired? Magic might not be readily available in your world. What about the formula for the potion, is it common enough? Etc
In my OSE Stonehell open table game I settled to 300gp/potion cost, with only 50% chance of availability each week. With an upfront (one-time) cost of 1000gp to bring the alchemist to town.
1. Consider also this article as a good resource on how to price potions of healing in games.
while flipping through Electric Bastionland this morning, I found the
general advice that TREASURE FOR XP should be bulky, expensive to the right person,
and useless. On the other hand, TREASURE FOR GEAR, meaning items that
will boost the PCs capabilities, should be useful for adventurers, but
have otherwise little value. This is awfully untrue for potions of healing. They are both expensive and tremendously useful for everybody. Taking a magical vial to recover illness and wounds sounds too good to be true, and would be highly sought after by anyone with enough coin. Right?