This is some idle musing that will hopefully wend its way to something useful or meaningful. I find it difficult to write large bits at once, so this will be something added to periodically.
There seems to be 3 economies at work in the game.
First is the brass / silver economy. This encompasses the transactions of the peasantry. It could be assumed that much of it is barter based due to this. It is an economy that adventurers quickly surpass as even the basic adventuring tools are priced in the 10-50 gp range. While it is the ultimate foundation of the economic structure of the game, given the extrapolations from the cost of simple labor and production of food, our characters and campaigns don’t spend a lot of time at this level.
Second is the gold / gem economy. Here are goods and services that are difficult to barter for with the standard commodities (chickens, skilled labor, bushels of produce, &c.). Here is where adventurers spend most of their time. Transactions are handled in 10s to 1000s of gold pieces, where select gems and art objects are used for higher demoninations rather than buckets of gold coins. (But that’s darn cool, too.)
Third is the land / magic economy. Here our conquerors and kings have control over a section of land and the wealth that it can generate. This wealth can be greatly significant, particularly over time. Also, significant magic items are able to be created by PCs. While scrolls and potions can be made earlier in their careers, they are relatively easy and low in cost. Here are the permanent magic items (swords) or enduring charged items (wands) that can command sums that would be absurd if paid in simple gold.
Some of the problems I have had in previous games is when PCs and the campaign “shift gears” and enter a new economy. In what way is the supply of lesser economy items impacted when the shift occurs and how does the presence of higher economies affect the campaign before the shift?

Hi Baron! Great question. The answer is, of course, economic. Consider that the demand for goods by adventurers is limited by the supply of treasure held by adventurers. (In economic terms, demand is how people spend their money, not what they’d do with money they don’t have). So supply of gold/gems = demand to buy things with gold/gems.
At lower levels, the gold/gem economy is limited by demand. The adventurers don’t have a lot of gold and gems, so their demand to buy goods with gold/gems is limited. The higher economy does not affect them very much, except that they have to pay taxes, fees, and so on to the lords - the higher economy is a “sink”.
At higher levels, the adventures have a lot of gold/gems, so demand is effectively unlimited. Supply is the limiting factor. This is where the Equipment Availability and Hiring Availability by Market Class tables become important. Those are, in fact, some of the most important tables in ACKS.
For example, let’s say that the adventurers have accumulated 500,000gp from a series of crypt raids and dragon hoards. This enormous wealth is stored in a cellar outside of the trading outpost (a Class IV town).
But what can they do with the 500,000gp? A Class IV town simply can’t provide them with what they’d like to spend it on. It has nothing for sale over 10,000gp. Spending the money is going to require moving to a bigger town; or hiring a lot of craftsmen and commissioning them. But even hiring that many craftsmen will require a bigger town!
So the limits on equipment and hiring availability force the adventurers to gravitate into a larger economy as they become wealthier. However, the larger economies tend to be distant from the frontiers where adventure and opportunity await.
This, in turn, encourages the adventurers to establish strongholds where they can set up their own towns, crafters, soldiers, and so on, without constantly having to travel hundreds of miles to a large town. Doing this is very expensive, and drains them of lots of cash. It also pushes them into the land economy.
At this point, by setting up such a facility (with a private sage, alchemist, master armorers, shipbuilders, troop trainers, etc), they now have a very inviting target for their foes. That in turn means that they have to consider the defense of the stronghold and the surrounding region, etc.
That’s more-or-less how it plays out.

Thanks for the answer!
So when the amount of wealth PCs have increases beyond a certain point a natural surcharge develops. The PCs will have greater costs due to the quantity and distance of the goods they now desire. Buying one suit of plate for the fighter may be doable locally, but 12 for their manorial guard requires either importing and supporting the blacksmith or the cost of travel to a larger city.
Okay. An issue I’ve had in the past, and that concerns the Dwarven Machinist, is that there are classes that have higher monetary needs than others. For the most part, it is actually fairly minor. I’ve never noticed a problem with the fighters and thieves supporting the magicians and clerics when they need excess funds for spellbooks or silver basins. Enlightened self-interest can be a potent motivator.
However, in the past I’ve used the Alchemist class from the Bard Games supplement ages ago. Similar to the machinist, it is able to fabricate solutions to problems. However, like the machinist, the limitations on their power is economically based. A fighter can fight all day, or until he runs out of hp, anyway. A magician can cast spells until they are all used. But, the alchemist could prepare all the potions and devices they they wanted until the money ran out. I had to keep a sharp eye out for the amount of recovered wealth, and considered how that character would impact the game.
Now that is, of course, a skill that all referees need to have. But it seemed that even if the gold available was a bit high or low, the magician and the fighter kept par. What limits keep the machinist in check? There is the gp / level per unit limit, but with a good haul, is there a horde that marches forth from the machinist’s workshop?
Edit: Actually, as I look over costs, a 4 HD minion with AC 6, 1 attack of 1d8 (sword) or 1 attack of 1d4 (thrown blade) and a range of 40’ would cost 28,000 gp for the blue print (one time cost), 28,000 for the library (one time cost, applicable to other projects), 28,000 for the workshop (one time cost, applicable to other projects), and then 28,000 gp for each unit. You spend over 100K just to get your first one.
That seems to point to a reverse problem, how could a 4th level machinist make one?

Since gold yields experience points in ACKS, whatever amount of gold you place should (unless I’ve royally screwed up) keep the characters at par.
For example, if the campaign is gold-rich, everyone will level up faster. Leveling up faster will make fighters and mages more powerful. Machinists will be able to use the gold to make better machines. If the campaign is gold-poor, everyone will level up slower. Fighters and mages will be weaker. Machinists will have less access to gold so weaker machines.
It CAN happen that, if the party splits everything equally and leaves no money aside for “adventuring needs” like scrolls, automatons, and so on, that a class like the Machinist might lose out. But that is more a problem with the group not willing to allocate the resources towards having a Machinist in the party, I think. A very selfish group is probably a bad fit for the class.

Alex: “Since gold yields experience points in ACKS, whatever amount of gold you place should (unless I’ve royally screwed up) keep the characters at par.”
You know, it has been so long since I’ve played with that rule I keep forgetting it and the consequences thereof.