So, what are some of the main pillars of a fantasy economy? Since it's sort of the mental baseline, let's assume a pseudo-medieval setting, with a mostly farm-based culture, and most of the wealth clustered in the hands of a few.
How much wealth does a typical peasant have? How much does his labor cost? What kind of stuff does he use that money to buy?
To begin with, the typical peasant has no coins or very very few. He has wealth, but it is in the form of durable goods owned collectively by a family - simple furnishings, a house, tools, cookware, clothing, livestock, etc. The total value of this property probably does not exceed 3,000 s.p. He makes about a s.p. a day. The property he owns represents probably more than a lifttime of labor creating. If it is destroyed, destitution follows for years and perhaps a whole generation. The peasant's primary source of wealth comes from his ability to work a bit of land productively, growing wheat and grains primarily, but also cutting firewood, and foraging pigs in the forest. If the peasant is wealthy and fortunate, he'll also raise doves, rabbits, hops, keep bees, make hay and straw, cut rushes, catch fish, etc. There may also be some simple cottage industry, such as thread making. The peasant gains wealth primarily by negotiating rents (or taxes) with the landlord - a noble who legally owns the land the peasant works. These rents will generally not be in the form of coin (that the peasant doesn't own), but a cut of the long list of resources that the peasant produces as well as a certain amount of labor from the peasant on the noble's fields or in the local militia. The peasant makes out well generally in good years, but since he must make the rent no matter what, drought or frost typically mean deprivation and starvation.
The peasant gets a meager amount of coin by taking his products to market on fair days to be sold generally to middle class buyers who don't work land themselves or who plan on working the raw materials into crafted goods. This small amount of coin is usually almost immediately eaten up in taxes and buying tools from craftsman.
What about a middle class merchant, who probably lives in a city as opposed to in the country? How much wealth does he have? What does he spend it on, and how much does that cost?
The middle class merchant has coinage and works in a money economy. The total value of his property is probably around 15000 sp., of which perhaps 1% (150 s.p.) might be in liquid assets of some sort. This is the merchants working capital with which he conducts day to day business. If it is lost, the merchant will likely have to borrow money (if he's able to, which isn't a given) or sell off his property at a fraction of its value to cover his capital needs. The merchant is engaged in a skilled industry of some sort. He pays his tax in coin. While he is forced to pay relatively steep fees to the local guild, the guild maintains a monopoly allowing them to charge extremely steep prices to the destitute peasants. For this reason, the merchants are probably hated as much or more than the landowners. The merchant has a considerable income of 5 or more s.p. a day and while no one in this economy is truly wealthy by modern standards, he lives as comfortable of a life as the technology allows, and has considerable time to invest in leisure and to engage in labor he finds intellectually stimulating. His principle concern is finding buyers. Once he invests his limited capital in producing some good, he's on a clock. He must recover his capital quickly or he'll find himself in a downward spiral. For this reason, the merchants will keep minimal stock and try their best to work on commission and with as much money in advance as he can get. If he cannot get money up front (which is often in the case of a noble buyer) and a buyer rejects a finished product, the result can be disasterous.
Clothes and linens consistute a not insignificant portion of the merchants valuables. Cloth is expensive, and its a mark of the merchants wealth that he owns several changes of clothes made from good cloth. A considerable portion of the merchant's income goes toward keeping up a standard of appearance which demonstrates his integrity and good character, for otherwise he would cease to be welcome in business ventures, be unable to borrow money, and so forth.
How much wealth does the mayor of a small town have? The mayor of a city? Leader of a county (what, Duke? Lord? Baron?)? How about a king?
It's hard to answer your bigger questions, but we can probably look at the question of, "How much money does the landlord have?" The landlord is a member of the lesser nobility, often a knight who is in service to some greater lord. He has several dozen families who support him through rents, as well as his own considerable property - which is generally the most valuable in the area. He maintains a monopoly on certain products (like venison) and owns the mill where everyone is required to grind their grain. (Miller's are absolutely loathed; they are the chief taxman of the community.) He has property worth 90,000 s.p. or more (not counting the value of the land), but we must certainly not imagine this as coin as mostly its going to be a more plentiful version of what the peasants own combined with what the merchant owns. The chief concern of the noblemen is keeping up his highly expensive equipment - armor, horses, etc. - and the household of retainers required to do so. His income probably amounts to 20 or more s.p. daily. However, upkeep on his military gear alone may cost him as much as 2000 s.p. a year. Although the nobleman is many times wealthier than his peasants, and has virtually unlimited leisure time, because of limited productivity and technology he doesn't necessarily live that much more comfortably than the peasants. Starvation is not a serious threat but disease is a threat to everyone, and because he's essentially an active member of the military in a state that is continually at war, his life expectancy is actually significantly shorter than the peasants that work his land.
If things go bad for a noble though, he can find himself heavily in dept. The loss of an eldest son (or several) and all the gear and horses that go with that, or gambling debts, or bad investments, or mismanagement of his own property can render the noble wealthy in theory only - unable to raise sufficient coin to cover his expenses and unable to wrest away the land he in theory owns from the peasants who have a legal right to use it. It's not impossible that the noble finds himself poorer than the wealthiest of his peasants, and forced to borrow money from them - which in turn leverages the peasant to better and better terms on his rent and in the case of the most industrious serfs, their freedom.
And where in this scale should we find your typical soldier?
Your typical mercenary lives no better than a peasant, is paid scarcely better, and does not have the stability of the property and land that the peasant's family has built up over time. He's also less well respected socially than even the lowest serf, as his trade is considered dishonorable. He scant possessions. The typical soldier hopes to be involved in the plunder of some great city or wealthy enemy camp, and from the spoils of war that he can share or steal (depending on the terms of his service) raise enough money to buy a small farm and live comfortably as a free yeoman farmer. Often, he's disappointed in this desire, dies of disease or exposure or infection from wounds recieved in battle, cheated of his wages, stripped of his meager possessions for being on the losing side, reduced to destitution, beggary (which is illegal), and/or banditry. A few however return home to respect, with a fortune, and the prospect of an honored old age.
A soldier that distinguishes himself well enough to be recognized as a Captain of a company has a much better chance of retiring from his position with honor and wealth. He's less likely to be cheated of his wages and far more likely to be allowed a share of the plunder. A suit of plate, a sword, and a saddle can be worth more than the several years wages of a peasant, and so a small share of plunder of a successful compaign can mean retiring to a comparitely good life indeed, hopefully in the care of some young caring attractive woman. Such successes are often the foundation of the few free farmers in the community.
See landlord.
A high ranking Lord-Captain such as a Marshall, a Marquise, a Duke, ect. is as a landlord only 100 times more so with daily incomes (and costs!) exceeding the yearly incomes of peasants by several fold. His wealth comes from taxing the landlords, directly through various contrivances (legally required marriage gifts, inheritance taxes) and indirectly by forcing them to serve for a certain period each year in the army. The Lord-Captain in turn often tries to get the knights to buy themselves out of this service (because they don't want to die) and hire cheaper mercenaries instead.
The main thing a high ranking noble wants is a castle and more land to support it. With a sufficiently fortified castle, the noble essentially has the ability to thumb his nose at a higher ranked noble when he wants or needs to.
What about a famous entertainer (bard)...
Essentially, this is a beggar that has a way to get around the laws against vagrancy, and he lives a life comparable to that. If he's fortunate, he earns a request to attend some noble, which means good food (or at least good leftovers, dinner leftovers being part of the wages of most servants with there being a strict pecking order over who eats first) and possibly a handful of coin. If he's really fortunate, he ends up hired in some upper level nobles court, where he'll live the comfortable life of a courtier and have a steady source of food and spending money. If he doesn't gamble it all away and isn't otherwise cheated by other courtiers, he'll probably retire comfortably with a modest savings and the care of children who can carry on his father's work because of the reputation his name confers.
a revered philosopher (cleric)
See bard. Or, if landed, see landlord.
the leader of a gang of thieves (rogue)
See common soldier.
the dean of an academy (wizard)
See bard. Or, if landed, see landlord.
