I like this because it's what "merchantile" is all about. Being a merchant, buy item from one place and sell in another, is hell of a role play.
What are the challenges in making this mod happen? I'm trying to make a list:
1. what triggers the change in price to happen? First of all, each town/city should have its own specialized products that tend to be abundant around that area. For example, town A has a lot of fish meat produced because it's near a large water body, and thus fish is cheap there; town B is near grasslands so it produces a lot of mutton, thus mutton is cheap there. This doesn't have to change over time.
However, if the price doesn't change over time for the same place then it'll become boring. Maybe when the following happens, the price of a certain product will change at a certain town:
A. a dragon attack halts production, thus increasing price;
B. when player buys/sells the same item in the same town, then the price changes accordingly
C. Price change happens in smaller scales randomly
2. how "active" does this economy system need to be? If you played Mount&Blade w/ Fire&Sword, you probably know how difficult to find a good trade route and how frequently it changes. If it changes too often and player must find new route constantly, it'll become frustrating; but if it doesn't change too much, then players will abuse it and lose its fun.
how do you think?

