In the World of Mythandar©, as in any world, people trade. No one is completely self-sufficient, though frontier folk living on their own in the wild come the closest. Farmers grow crops and raise animals and frontiersmen harvest skins and timber. Market places and trade districts in every town and city are filled with shops where goods are traded. And though much commerce is conducted as barter, every civilized land uses coin of gold, silver and copper, each with a set value.
1 Keshite gold enk = 2 Imperial crowns
1 Imperial gold crown = 2 Anglamarian gryphons or Varalyan eagles
1 gold gryphon or eagle = 10 silver moons or cartheens
20 copper pence or obles
1 gold dwarven strike = 2 Imperial crowns
4 gryphons or eagles
40 moons or cartheens
5 silver tradebars
10 iron tradebars
The value of goods varies by season and region, and fluctuates according to supply and demand. A bag of flour might sell for 5 pence in Middlefields in Summer, and three times that in Northinghall at Mid-Winter. A good riding horse at Aragond might cost 8 silver moons at the height of trade season and only be worth 4 in Beregond in Winter when feed is expensive - unless the Baron is outfitting his troops for the field. Then you might be able to sell the beast for a gold gryphon. In general, it's a seller's market.
For Player reference, consider the silver piece (Anglamarian moon or Imperial cartheen) as the standard "dollar," and extrapolate probable prices from there. Use common sense - if a mug of ale at the local tavern costs 2 copper pence and a horse from the local trader runs around 5 silver moons, that guilded suit of platemail in the armorer shop will probably set you back more than 1 gold gryphon.
Horses range in price, depending on breed and quality. The average horse, broken and suitable for travel, runs around 5 silvers, while a high-bred and trained warhorse might fetch as high as 5 gold.
Travel gear, including a pack, bedroll, small tent, fire-making kit, knife, axe, a waterskin or canteen, and a week's worth of food, costs about 5 silver.
Clothing varies widely in price. Common, servicable clothing (tunic, trews, a cloak and boots) costs around 10 pence. Warm winter clothing would be double that price, at least. Fine or dress clothing can range from a few silvers to several gold.
Tavern and inn services are fairly even across the land, depending on the season and location. A typical room for one or two can run a silver moon each night, while stabling and fodder for a horse can double that price. A hot meal costs a few coppers, while drinks vary according to quality and rarity - anything from two pence for a jack of ale to several gold for a bottle of fine wine.
Armor costs depend on type and quality of work, of course. A good set of studded leather fetches 5-10 silvers in any town or city with a skilled leatherworker. A chainmail hauberk could easily run 2-3 gold gryphons in Anglamar, since mail is highly prized for its protection and versatility. Plate mail armor is rarely sold openly in armor shops; it must be fitted to the wearer and can be quite ornate. In general, any craftsman with the skills and facilities to produce plate mail armor has the luxury of naming his price. A plain suit of armor, without guildwork or ornate design, can easily cost 10 gold.
Weapons, as with armor, vary in cost depending on quality and ornateness. A plain servicable fighting dagger would run around 1 silver, while a well-forged greatsword would easily be 2-5 gold. Longbows are cheaper than the arrows they fire, while powerful crossbows are expensive (around 5 silver).
Traders transport goods from the farms and frontiers to marketplaces in towns and cities. They purchase draft animals and wagons from locals in order to get their goods to the town merchants. Traders also hire armed guards to protect their cargos from bandits (as well as rival traders).
Tradesmen in the towns barter for some of the goods and produce staples - flower, feed, leather, clothing, iron, worked lumber. Much of it is used locally. Blacksmiths produce tools, carpenters work the lumber into furniture and construction materials, brewers and millers use the grain. Some of the raw materials and finished goods are sold to traders.
Merchants do business in every major city, buying from the traders and either stocking local shops or selling to shippers. Goods are loaded aboard ships at port and sent afar, while foreign goods are brought in and traded back down the line. Some of those goods end up back in the hands of the farmers, frontier folk and miners.
Nobles sit at the top of the pyramid, collecting taxes from all trade and commerce conducted on their lands. Minor officials and agents of the nobility take their own cut from the traders, tradesmen and merchants in the form of gate and road fees and simple graft.
Along the way, there are countless small concerns that survive on the flow of trade from farm to town to city and back again. Taverns and inns, provisioners, livery stables, cartwrights, horse and oxen dealers. Let's not forget the thieves, brigands and pirates who prey on travelers, traders and merchants.
Trade Guilds exist in the cities and tradetowns of Anglamar as associations of businesses, from bakers and blacksmiths to fishmongers and taverners. They agree on prices and contribute to the improvement of streets and sewers, hiring private guards and other projects for common benefit. In some cities, like Gondaran and Aragond, the Trades Guild wields considerable influence in city government.
The Merchants' League in Westhaven is a powerful union of wealthy merchants who control the flow of foriegn trade. They own ships, large warehouses and trading costers, doing business with the local merchants and traders to distribute goods. In Anglamar, they form a wealthy "middle class" between the peasants and the nobility (and in truth, many of them are wealthier than some nobles). The League virtually runs the city of Westhaven, and they have influencial representatives in Beregond, Aragond and Arandor.