There is no such divider in material and labor cost. The component cost is just how much it costs to pay for the materials and the labor to produce it.
Impossible, the current cost of the Gold Age foundation is low. Which is impossible to attain if the cost of labor includes weeks or months of archmage level enchanter labour.
The same could be said for the Runic Inducer, I doubt ANY amount of runesmith labour could be considered a "negligible" cost.
All evidence points to material costs being just that, the costs of the materials (and perhaps tool usage).
I see no reason to assume that the cost increases exponentially the way you did. You made the assumptions, and provided no proof to back either of them up. There is no such evidence.
We've been told that the cost are adjusted to a nations level so you have to ask yourself what is trivial, low, moderate, high cost for a ruler? My guesses :
Trivial or negligable are probably any thing below 1-10 gc.
Low would probably be the cost of a very small building or small renovations perhaps.
Moderate would be a moderate undertaking, perhaps a regular sized building or important renovations.
For something's cost to be considered high to the WP's clients, I'd say it's probably on the level of major infrastructure or a small military campaign. Luckily, none the choosen components are at that level of material cost .
There is even evidence against it. We know that the costs across the categories are broadly compatible, for example a low cost component in one category costs about the same as a low cost component in another. Two capstones have a negligible cost: the Stone Flower and Runic Inductor. The Carved Rune also has a negligible cost. The Stone Flower relies on High Magic, and enchanters who can do High Magic are not a common resource. But the component is as cheap as hiring a stonemason to carve the rune and hiring apprentice runesmiths to carve two runes.
The component cost is just that, components it doesn't include the labour cost.
We can conclude that while a runesmith is needed to build the runic inductor, the cost of materials is trivial to a nation. Just like the cost of materials to crave a mundane rune into stone is also trival (lol chisels?).
On the other hand, the quantity of materials and usage of tools needed for a runesmith to carve the waystone rune is considered low instead (better quality tools, regents, etc.).
Of course, the cost of having your rune cast by a runesmith rather than a mundane mason is bound to be many times higher.
