What is the relative value of 1 Coin in the implied setting of Dungeon World?
The game system of Dungeon World intentionally keeps the concept of money and wealth fairly abstract compared to other, more simulationist systems. The equipment section of the rules list costs in a manner clearly intended to only be taken in the context of "adventurers purchasing adventuring gear during an adventure", such as having simplified numbers of coins modified precisely by a character's Charisma score; it should probably not be taken to mean that all the NPCs use these rules themselves all day every day.
While this simplifies and expedites the bulk of the shopping that is most frequent in the game and slides over the stuff that is largely unimportant - as Dungeon World is excellent at doing - it leaves a logical void in the event that the story does take a turn that involves wealth or economics in some significant way.
How much does the typical Peasant Farmer or Commoner make in a month? If a DW group comes across 100 gold coins, is this a staggering "more wealth than a commoner has ever seen", or a more modest "a solid stack of money, but nothing outrageous"? What would be considered a "fortune", a "king's ransom", or "enough riches to retire in lavish style"?
How does 1 Coin in Dungeon World compare to 1 Gold Piece in Dungeons and Dragons? D&D being a popular game that does answer these questions and has a (deliberately) similar system, how do the currencies compare? A valuable listed item in making a comparison is that of food, which seems to be priced higher than D&D. However, weapons and armor seem to be priced much lower. It seems that things that commoners would need to worry about (food, shelter) are more expensive, while adventuring gear (weapons, armor, travel gear) is cheaper. I suspect that 1 DW Coin is, in general, worth less than a D&D gp, but probably more than a D&D sp.