At the moment tradegood prices just depend on the amount of total production, rather than actual supply on the market.
The supply element of tradegood prices should be based on the actual amount available on the market, using totals of SELL_declare available.
Set the price at game start by doing a SELL_declare_available to every TZ, then get the demand in that TZ. That is the TZ's price for the tradegood. This can then be modified by the global supply and demand anyway, as a general uptick in global supply should lower the price anyway.
Then, every quarter, during the international trade phase, update the TZ prices for the next quarter.
At the moment tradegood prices just depend on the amount of total production, rather than actual supply on the market.
The supply element of tradegood prices should be based on the actual amount available on the market, using totals of SELL_declare available.
Set the price at game start by doing a SELL_declare_available to every TZ, then get the demand in that TZ. That is the TZ's price for the tradegood. This can then be modified by the global supply and demand anyway, as a general uptick in global supply should lower the price anyway.
Then, every quarter, during the international trade phase, update the TZ prices for the next quarter.