...it Increases the cost that Journey men must pay to become masters, both for runesmiths and regular blacksmiths, this will likely result in them increasing prices across the board for even their basic products to reach the required amounts to afford whatever they need to become ordained masters.
This means that any product needed from these people will increase in price which will trickle even further down since the price of belt buckles, horse (goat?) shoes, locks, axes, pickaxes, etc. will increase. which in turn will effect the price of other products that need those pieces of equipment, ores, fortifications, household products, etc.
So yes I'd consider it a cornerstone product due to how it's linked with the greater current economy.
Okay I think I've identified your problem. What you need to understand is that Runesmiths are really rare. They need to be a descendant of Thungni and they need to have the gift. Snorri aside because he's enough of an outlier to shift the mean, dwarves don't have enough runesmiths to make everything have runes.
And Blacksmiths don't have to work in Gromril.
Additionally, gromril is only one of the ingredient costs of runic items,
The cost in reagents, material, the money not gained from doing commissions, it all piled up into a terrible beast that threatened to swallow her savings whole.
Like feeding a ravenous maw.
There was a reason why it was a common thing to see Journeymen Runesmiths braving the wilderness for reagents besides the challenge of it, and it was because it was actually more economically viable than buying everything they needed. Even her own research costs were being discounted by doing the same thing whenever she could and they were still eating up her earnings like a parched dwarf guzzles ale.
So here we see that in addition to gromril, a large amount of a works cost is in the reagents. And additionally that a lot of Journeymen struggle to afford to be runesmiths due to the cost of them.
Karstah nods and thanks the elder for his patronage, watching him leave her humble shop out of the corner of her eye while she starts running through the month's budget.
Reagents secured, material costs met, I'll have to put off the research for another year to finish the commission from One-eye but I should be set for another five years afterwards…
Here, we see that a single commission can sustain half a decade of research for a journeyman. I hope this makes the price of these objects apparent and obvious that they aren't day to day objects for your average dwarf.
You watch from several meters away, sitting on a bench and eating some stonebread, as Dolgi leaves yet another shop empty-handed. From the looks of things, he's been doing rather poorly lately. Not in terms of quality, because you'd throttle him if he was making shoddy work, but in terms of getting any real work to do. The troubles of having so many Runesmiths in a hold is that there's always someone to compete against. Course the lad's got the chops, just seems like a run of bad luck. Nothing really impressive for him to do and prove himself, just a lot of more mundane Runework from your observation. He's got enough money to get by for centuries, but it's clear the lack of any real work is affecting the young lad. Of course, you also see him clench his fist and tug on his beard, energy seeming to fill his veins as he likely makes an oath to overcome the challenge.
Here we can see that it can be difficult to get those commissions in the first place.
Somethings to note are 'having enough to get on for centuries' kinda contradicts how rapidly Kharstah appears to eat through her money, this might be an indication of how high research costs truely are Dolgi has enough to eat and feed himself for centuries but that doesn't include research(?).
If that is the case however, we can estimate just how high costs are as a journeyman who is actively researching and creating items burns through savings at least 20 times faster than a dwarf who is not. Taking this adjustment the 5 year commission represents about a century of living costs for the average dwarf, probably millions in our currency.
Honestly the idea that theres mundane runework that can sustain them is a bit confusing to me, presumably this is stuff like making runes of light en-masse, and I wonder how that works in more conservative holds where they more strictly hold to the rule of pride and can't rely on this. Maybe masters don't send apprentices on journeys until they have built up more savings or just more southern journeymen fail to make master. I'd be interesting in hearing more about this from soulcake I guess.
When a dwarf needs one of those things they go to a blacksmith and get a non-runic version usually, and that will be steel not gromril. And even if they did want a runic version, steel can also hold runes.
Prince Gimli is still carrying around a set of axes made by an apprentice ages ago. That he hasn't had them replaced by a master as he's grown up should probably be an indication of exactly how rare they are.
Kraka Drakk is extremely unusual in how common runic items are and that is because Snorri makes a ridiculous amount of goods and that when he did Hold Armings and the Underway, he did it as a gift rather than charging. Most dwarves will never own a runic item.