In my game for Japan, i see strange behavior of the prices in the market. For example, Japan produces 50 silks per turn, sells 30 in a world market and 20 on the internal. Demand for Japanese silk is 120, and stable. The price falls to 5.
Same thing for production = 90, world sale = 70, internal sale = 20. Price stable at 5, demand ~95.
It is strange that the need for the goods isn't satisfied, and the price on a minimum.
Probably, it is considered not only balance of supply and demand, but also stocks of the goods?