Currencies
Copper (10 = 1 silver). A petty unit of currency, used by common folk for small everyday purchases. Used for things like beer, snacks, tolls, small repairs, lodging for a single night in a roadhouse, and so forth.
Silver (10 = 1 gold). The dominant unit of currency, used for significant things like equipment, lodging, transportation, and monthly living expenses. The value of most objects is measured in silver. The value of silver is typically backed by bushels of cereal crops.
Gold (10 = 1 platinum). Gold is rare, and used by the elite for major transactions or the purchase of very expensive goods. Examples include suits of armor, vehicles or ships, spellcasting services, etc.
Tradebars (100-500 silver). Tradebars are small ingots of precious metal, usually silver or gold, that have a fixed weight and are stamped with various seals to verify their weight and value. They are used by trade cartels, noble houses, major guilds, and rich merchants for large commodity transactions like grain, oil, warships, etc. Usually tons of grain.
Living Expenses
Poor (10 sp/month). A simple bed in a shared room, common area, or flophouse. People at this level of income are cheap laborers, beggars, refugees, and so forth. Foods at this level of income include bread, porridge, vegetables, fruit, eggs, rabbits, smoked fish or shrimp, and tea. Legal protection is minimal.
Modest (20 sp/month). A small room in a shared household or tenement. People at this level of income are servants or paid laborers with minimal skills, common soldiers, and similar. Foods at this level of income also includes stews, beans, cheap sausage, mutton, chicken, honey, and weak beer. Legal protection is basic.
Good (30 sp/month). A small house, suitable for a family of 3-5. People at this level of income are successful tradesmen or small business owners, usually part of a guild. Foods at this level of income also includes pies, pastries, soups, cheese, wine, smoked pork or bacon, fresh fish, and a variety of spices. Legal protection is good.
Affluent (40 sp/month). A substantial house suitable for a large family, with an enclosed yard or garden. People at this level of income are high level tradesmen with valuable skills, military officers, and similar. Foods at this level of income also includes beef, duck, venison, chocolate, coffee, sauces, and extravagant baked goods. Legal protection is excellent.
Extravagant (50 sp/month). An estate, with the support of a wealthy organization or noble family. People at this level of income are landowners, government officials, high ranking military officers, and similar. Foods at this level of income are more extravagant versions of those enjoyed by the affluent, with spices and sauces. Legal protection is absolute.
Money
Money is an important element of fantasy settings, though it can take many forms. The most common form of money is coinage: a classic old-world institution based upon the idea that certain metals have intrinsic worth due to their rarity. Coins are not worth anything in and of themselves; they are a social contract. The concept of “Loot” and “Riches” is so deeply ingrained in the fantasy genre that you can’t divorce the two. The value of a coin is determined one of two ways. The first way is the weight of the metal it’s made from, and in this system larger heavier coins made with more precious metals are worth more. This is how hacksilver works.
Using weight as a basis for value has several problems. Coins are heavy and hard to transport, the population may get too large and there might not be enough metal to support its currency needs, or if there are too many coins in circulation you have to worry about inflation.
The second way is to base the value of coins on a commodity that everyone needs, which regulates its own scarcity through spoilage. Ancient economies are usually AGRARIAN, meaning they’re based on farming. This means cereals, or grain crops, determine the value of money. In feudal Japan a single KOKU represented a years supply of rice for one person, for example. Using this method coins can be made very small and portable; you can cut holes in them to save on metal and string them through knotted ropes to create “strings” of cash, like they did in ancient China. The local government recognizes their value based on bushels of wheat or apples or whatever.
Using coins for currency also influences taxation. It’s hard to prove that someone got handed a bag of coins if they aren’t tied down and easy to audit. In a fantasy setting, businesses and landowners pay most of the taxes because they’re the easiest people to tax. That also means the government protects these people more than anyone else. It’s even easier to tax a guild that collects fees and dues from its members. If push comes to shove, the local authorities will always side with the guy who owns his own establishment and keeps his books in order. This means “not adventurers”, since they’re often a bunch of murder hobo transients, looting their way through life and hiding cash in bags of holding buried in chests in the desert.