The Aquill and Economics

The followers of Aquillus mint a coin known as the aquill made of solid gold. This coin has become so renowned for its reliability that it has come to serve as the base standard of value throughout the world. Even regions with other currencies usually recognize the aquill's value and convert easily between it and the local currency, if they don't outright prefer being paid in aquills.
An aquill is a standard day's wage for an unskilled laborer. While converting between modern and ancient currencies is difficult, you can think of it being roughly equivalent to a $100 USD bill. You would not pay for everyday transactions with an aquill coin, and in fact most people would not be able to give you change for such a large denomination.
When considering the value of an aquill, remember that in a pre-industrial society everything is made by hand. In our modern era, $100 USD would be enough to buy several outfits, thanks to the power of mass manufacturing. However, in the classical age, all clothing is stitched by hand on hand-woved cloth made from hand-spun thread made from plants that were planted, harvested, and tended by hand. A single basic outfit will cost several aquills.
As a rule of thumb, you can take the price for an item at a renaissance faire and divide by $100 USD to get the price in aquills for any given item (though food is usually fairly cheap).

Living Expenses

The more you make, the more you want to spend. As a rule of thumb, an adventurer will spend their level in aquills on daily living expenses. At low levels, this is nights in an inn, rations for the trip, replacing ammunition and repairing equipment, as well as probably a few small luxuries. At higher levels, as wealth flows more freely, those who earned it will want to do something with it besides simply buying better equipment. Here are some ideas to give players inspiration as to what to spend their living expenses on.

• Entertainment: Quality food and drink, company, better lodging, vice.
• Charity: Donations to people and causes who deserve it. Maybe sending money home to family.
• Investments: Loans, buying land,

Hirelings

In general, unskilled laborers make 1 aquill per day. If they are skilled, a good rule of thumb is their high stat in aquills each day. So if you want to hire a scribe to transcribe your novel, and they roll at a 3 to craft, that will be 3 aquills per day plus the cost of components. Assume a typical workday of 10 hours and divide the cost by 10 if you need someone for less than a day.
This is for everyday work. If your hireling is doing something particularly dangerous or unpleasant, these costs can be multiplied again. For high-stakes crime or battles where death is routinely on the line, a multiplier of at least 5 comes into play.
Workers of incredible skill are so rare that they have the power to name their own price. A worker with a high stat of 7 is of legendary skill, world-renowned for their ability. Such a person only comes along once in a lifetime, if that, and history will remember their name. They're unlikely to be motivated by anything as pedestrian as money, though if they are, their prices will be exorbitant.