We have numbers for where goods and services are, and we have a method for how to get translate that into numbers. And we have a system for the distribution of those articles. Any questions so far?
Let’s move on, and see about how to work out the price of an actual item. This is going to get fairly complicated, so get out a pen and paper and follow along. In this case, showing the work is de rigueur.
Thankfully, I don’t have to work through this process every time. I have it on excel, with each formula automatically translating the numbers; but I’ll go through it here, so it can be understood how its done. Sadly, my price table is behind my source table, the one I posted yesterday, as I spent last week adding France. Therefore, these numbers will not fit; that doesn’t matter. I’m not in the mood to update my price table at the moment, which will take three or four days…I’m working on other things. It is the SYSTEM that matters, not the numbers.
(You wouldn’t be using these numbers anyway—you’ll be using the numbers generated by your world).
The numbers apply to Kronstadt, where I believe I’ve mentioned the party is near. The importance of the town is that it occupies a gap in the Transylvanian Alps, as a gateway between the Great Hungarian Plain and the Black Sea.
Okay, disclaimers done. Let’s start with iron ore.
Total Iron references (at the time of the making of this table) are 319. Of this, Kronstadt imports 6.565. You’ll remember that this is the product of various market zones all feeding into Kronstadt depending on how far away they are.
The 6.565 is computed against total world production, and we find that Kronstadt has access to 1,622,076 stone (16 lb.) of iron ore (metal equivalent). This is worth 13,727 ounces gold; translating this into copper pieces per stone (64 c.p. per g.p., plus 2 grams gold content per g.p. which means 15.55 g.p./ounce of gold…remaining coin content is typically copper) gives us 8.42 c.p. per stone.
To this, I apply a travel modifier divided by 1% of the world’s total; Kronstadt’s comparative availability is 2.1% of the world’s total…that means the 8.42 c.p. is divided by 2.1, giving us a cost of 4.09 c.p. per stone of metal content for unprocessed iron ore.
Okay. Pig iron:
The smelting references for Kronstadt are those for smelting in general and for smelting specifically iron ore, which adds up to 4.743. (From this point on we ignore the world’s totals…those only apply to the raw materials). The base price for smelted iron (pig iron) equals (ore price)/4.743+(ore price). In other words, the greater the number of references available to Kronstadt, the lower the service cost of transforming it into pig iron; a reference of “1.0” would exactly double the cost.
Thus we have (4.09)/4.743+(4.09) = 5.0 c.p. per stone. However, it requires 5.67 stone of coal and 0.72 lbs of limestone added to the blast furnace to make one stone of pig iron. The cost two raw substances is also worked out, and in total they add 64.8 c.p. to the final cost…giving us a final total of 69.8 c.p. per stone of pig iron.
Wrought Iron:
So far, all we have is puddled metal…it is not even as far as it needs to be for it to be smithed. It has to be mixed with other metals…specifically manganese and nickel. There are hundreds of wrought iron combinations; I use one I found in the old encyclopedia, which is common enough for use here: 93% pig iron, 6% manganese and 1% nickel. 0.93 pounds of iron costs 4.1 c.p.; 0.06 lbs. of manganese is 1.2 c.p., and 0.01 lbs. nickel is 0.9 c.p. This is 6.1 c.p. total for the raw materials.
The availability at Kronstadt for metallurgy, or the making of alloys, is 1.806 references. Once again, 6.1/1.806+6.1 gives an adjusted price of 9.5 c.p. per pound of wrought iron. Now we can move on to smithing.
Ironmongery:
The availability of iron smithing in Kronstadt is quite high; Transylvania was famous for its metal working, which was part of the reason it was able to oppose the invasion of the Ottomans for so long. Even as Hungary fell in the 1500s, Transylvania continued as a “client-kingdom” of the Ottomans, enjoying soveriegnty in their own country in trade for the occasional force of men and the much needed metal goods it was able to provide the much, much larger empire.
Transylvania’s references for ironmongery is 3.72. Applying this to the price of wrought iron (9.5/3.72+9.5) gives us the quite reasonable price of 12.1 c.p. per pound.
This can now be translated into actual goods. Of course, the party could, if it wished, buy bars of wrought iron. At 9.5 c.p. per lb., a 20 lb. bar of iron would be a mere 170 c.p., or less than 3 g.p. Of course, if a first level party broke into a smithy and found a stack of 400 such bars, it would make a tidy little treasure. Moving it, on the other hand, might be interesting…but a smart little adventurer might figure that out, and just how high a level can a blacksmith be?
Well, I’d estimate fifth level. But if a thief snuck up behind him at just the right moment…
But I digress.
Lets take a very simple piece of ironmongery: a catapult ball. For a small catapult, my sources tell me this would weigh 57 lbs. All we need do is multiply the catapult ball’s weight against our known cost for ironmongery, giving us 689 c.p., or 11 g.p.
Of course, not all ironmongery is built equally. Some things are harder to fashion than others: for different things I assign a level of workmanship. I try to keep the numbers low…twice as hard, three times as hard and so on. An anvil might be 1.5 times more difficult to craft than a catapult ball; a door, being nothing more than a poured square with a hole for the handle, 1.75 times. A cauldron, which must be balanced, 2 times. A chain, 4 times. And so on.
Here is a list of the ironmongery items I’ve added to my equipment list:

This is not exhaustive, by any stretch of the imagination. I’m sure there are things missing. But to get the price for those things, I do not have to pull one out of my ass. I can judge its workmanship by other items on the table, determine its weight and there you are. Plus the comparison between the objects makes sense.
The above list, you'll also notice, contains no tools...that is the next tier, in which tools are more expensive than ordinary iron objects.
And if the party moves to a place where iron doesn’t happen to be common…say the Guinea Coast of Africa, the reference numbers go down and the costs go up. Or the reverse, say in Alsace-Lorraine in France—where every party ought to go to buy their weapons.
Does this help fill some of the holes in how my trade works?