Currency
The economy in the Familiar Lands is unified under 4 different denominations of value.
First is the Copper coins, they are the lowest denomination of currency within the realms. 2 copper could be used to purchase a candle or a torch. 3 copper coins could purchase peasant's bread, which would be enough to survive on for a day.
Worth 10 copper coins, a single silver grail coin can be used to purchase a night's stay at a cheap inn. They can also be used to purchase subpar secondhand weapons, or a flask of cheaply pressed cooking oil. These coins are commonly used by commoners, and fledgling merchants.
Worth 10 Silver Grails, a Gold coin can be used to hire the services of a capable Knight/Mercenary, or to pay for extensive healing services from proper establishments. Proper plate armor might cost a few gold coins depending on the material it has been crafted from, as well as the skill of the smith.
Then comes the Mythril Medals, these Medallions are worth 25 Gold coins. They are usually specially issued by banks and only carried by wealthy aristocracy members. They are usually used to purchase land and housing, or to request illicit services from a highly skilled mercenary/knight. There is an enchantment within these medals to prevent counterfeiting.