Some cool lore a member of the AoS Lormasters discord posted. From the Sons of Behemat Battletome.
"In the early days of the Age of Sigmar barter economies arose within many cities and nations. Eventually, coinage was trialled as the primary currency across the great nations of Order, with the Kharadron Overlords in particular enthusiastically backing the practice. The universal currency system that the Kharadron attempted to institute would eventually collapse due to the Goldflood, an event involving heavy inflation of metallic coins. As a result the barter system once again rose to the top once again. Eventually, a new currency arose in the form of Aqua Ghyranis, special water from the Realm of Ghyran prized for its healing properties. Aqua Ghyranis is widely exchanged between people and merchants of the Cities of Sigmar, Kharadron Overlords, Sylvaneth Enclaves, mortal kingdoms vassalized by the nations of death and many others across the realms. Other currencies have also risen to dominance as well, though not all are as widespread as Aqua Ghyranis. Such as the much-coveted Glimmerings of Excelsis, the Spiceblood coveted by Soulblight Vampires, Purebone which serves as a state currency of the Empire of Ossia, varied Realmstone currencies, Charm-silver tokens of Lethis, and many others.
In spite of the Goldflood, and the dominance that Kharadron Overlords have over the Spiral Crux and its precious metals, currencies in the form of precious metals and metallic coinage still persist. This is partially due to the Fyreslayers who in their eternal quest for Ur-Gold refuse to be paid in anything but gold and Ur-Gold.Non-metallic coins have also arisen in various regions across the realms.
The golden coinage of the Kharadron themselves has yet to recover after the Goldflood and massive stockpiles of mostly useless coins have been amassed throughout the Skyports. These are often used to pay for Gargant mercenaries, who value the enrapturing luster of the tokens more than their contents or what is stamped upon them."
He's really into the currency of the mortal realms.
https://ageofsigmar.lexicanum.com/wiki/Currency_of_the_Mortal_Realms