here is the TLDR: real life modeling of economics in DF means that DF will need the equivalent of real life tools to keep up with it. i am not an accountant or financer or stock market annalyser, nor should i have to be to play DF. DF's economy model should be simple, not complicated.
Someone doesn't need to understand the economy to participate in it, just as you don't need to understand Geology to play DF. All you really need to know is YOU HAVE STRUCK HEMITITE!
Likewise, in real life, you don't need to know much about the political policies of Iran, Russia, or Venezuala, global production or refining capacity, or the practices of speculators who essentially horde the world's oil supply until the world is willing to pay their ransom for it back to understand that, "hey, gas costs more than it used to!"
The current economy is the most simple kind of economy, essentially a "
Karl Marx Hates Your Guts" economy, where all goods have the same price at all times, except when you or they request something, arbitrarily raising the value of that good.
We can make the economy have a simple increase in complexity by making rarity alone modify value, but this doesn't really reflect anything realistic in demand, because it makes the only billon chair in existence worth many times more than more common copper or silver chairs or even gold chairs.
We can have a system where elves might want to demand more weapons based on a shortage in their civ, or a sudden interest in quarrey bush leaf meals without making the PLAYER track the global supply of iron. Likewise, humans may have a general civ-level wealth rating. When they are poor and desperate, they only trade for food or necessities. When they are wealthy, they will pay greater prices for higher-quality items and toys and luxury goods. All the player would need to know about this, however, is that they could hit the "c" button, and look at what the different civs are paying for different kinds of goods, and adjust what he/she is selling, accordingly. (I mean, unless a player really, honestly DOES want to meddle in fixing global prices of goods.) We certainly don't even expect the player to pay more attention to other civs right now other than to simply note that they exist in the first place.
Likewise, I don't even blink when my nobles start fussing over the price fluctuations of internal pricing of goods, since it makes no difference at all to my fort's operation. Oh no! That rope reed sock will now cost 308 DBs instead of 290 DBs because many people replaced their socks, and supply has gone down! This means next to nothing when my dwarves are generally gainfully employed, and it makes little difference since they're going to buy the thing if they want it, anyway. Who seriously wants to go micromanaging every single one of their dwarves' checkbooks?
The trader coming to visit really doesn't CARE how rare a good is in your fortress, only on what they can sell it for elsewhere. Their pricing should have NO relation to local conditions, and be learned only by trading and talking to the liason. Price histories should be available to the player so I can easily see that the dwarves are paying 2x as much for armor as the humans. Again, the accuracy of such tables would be based on the skill of the trader. Long term, I'd like to be able to set up trading caravans of my own that will let me send off a caravan of goods with predetermined trade priorities. Since eventually we are supposed to BECOME the mountain home, this kind of interaction with our subjects should become possible.
Within the fortress, rarity should absolutely be used to set prices. If I don't make many shirts, only my Baron should be able to afford shirts. I'd rather the rich be able to maintain their happiness than go shirtless because some hauler walked off with the only shirt. Nobles should mandate production when they are hearing complaints from all those having to go without socks because I forgot, and make mandates for 50 socks to reduce the shortage. That way I don't have to keep track of shortages, my nobles do it for me. This makes nobles a tool for monitoring the happiness of the people, and for making sure I don't have to micromanage. Ideally I could just assign a clothes maker to automatically fulfill mandates as a top priority if I don't want to be bothered. If done right, there need be little extra work for the player.
I'd like to back this notion, as well.