Just a fun fact for you, the book "The Wonderful Wizard of Oz" which was the basis for the movie, has been and can be interpreted as a satirical allegory about the gold standard and the effect it was having on farmers and mortgages in the late 1800s. The author, L. Frank Baum never claimed it was anything other than a childrens' book, but the symbolism and story are very strongly parallel to the Populist movement of Baum's day, and authors have analyzed it as such, not unlike the parallels some have made between the Lord of the Rings books and World War II with Tolkien.

Another children's author who's work has been linked to economics, though far more overtly in this case was Astrid Lindgren, the author of the Pippi Longstocking books. Lindgren was a self-employed author of children's literature in Sweden, where the political party in power, the Social Democrats, which she herself was a supporter of, enacted tax laws making her personal marginal tax rate effectively 102%. This was due to a combination of income taxes on employee wages and fees that employers were legally required to pay, and since she legally was definable as both an employer and an employee, she had to pay both.

There is the problem that the demand for Augments and Refinements will decrease over time. There are some caveats to that though:

1. That assumes players who have reached the level cap and have fully twinked out their builds keep playing and generating IGC and items they don't really need. In my experience, when I get to that point in a game, I stop playing, or play a lot less than I used to. And anyway, you can always make another toon to level and build with the IGC.

2. It is possible to make the process of getting to the cap and to the point of fully built take a long time. After all, we're likely to have like 100 slots to put Augments and Refinements into, per toon.

3. That can be less of a problem while there are new people coming in and playing the game from "square one". Newbies need gear.

4. If the making of useful Augments etc requires you to effectively destroy IGC and raw materials that go into that process, the fact that you're reducing the amount of both things in the environment will likely tend to slow the inflation rate. In GW2, the inflation is not bad, and there you do content and get mostly items, which are mostly worthless, but you can spend some IGC to de-craft them into raw materials, which are somewhat more valuable. They can tweak the drop rates of IGC and items such that it stays relatively flat, though some inflation is expected. Also, in that game, you don;t get any specific IGC or item rewards for every monster kill. Sometimes you just get XP. It's random.

5. I still like the idea of giving players temporary buffs to spend IGC on so as to give the capped and fully-build a reason to spend. I don't like the idea of making it a thing that you use all the time like Insps, but maybe a more substantial, but less frequently used thing would be good. Like the Warburg Nukes, the Jellomen, etc. In GW2 they have food crafting which allows you to make food items that when consumed give you a temporary buff. You can't stack different food buffs, so it doesn't get out of hand crazy, but there are tons of food options to choose from and a crafting system for it. There are even communal "open buffet" type things you can throw down and everyone can partake of.