Order of purchase would have to be totally remodelled from the original Vicky, to run in order of lowest-cost-to-buy first, which would finally give us a model where countries (amazingly) trade with other countries rather than the infinitely wealthy teleporting flying saucer of the WM. It would hopefully even make the idea of split markets redundant - no need for seperate region markets if the transport surcharges on the purchaser make distant goods unaffordable anyway. Unfortunately, I suspect that tracking the starting points of ALL goods on the Vicky map to end-points would have crushingly high-end PC requirements.
That's why I among others believe that separate markets are a good idea, since you don't have to calculate all those distances.
Additionally, how would this system of 'purchase orders' work? How do you make the link between your POP in London which needs grain? Are you going to look around for each POP? This would become a programming nightmare. For each POP, and for each government, there needs to be one place where it can buy needed goods, a market.
The transportation cost could be calculated at maximum three levels:
- between the factory / RGO and the market;
- between two markets, in case of international trade;
- between the market and the buyer.
This transportation cost could be calculated and updated for each region, depending on the distance with the Center of Trade and the infrastructure, because it should make calculations easier and quicker.
If we want to be even more realistic, the transportation cost could depend on the type of goods: heavy goods (grain, coal, ...), medium (furniture...) and light (clothes, precious metals), so that luxury clothes could travel easily around the world with a small transportation cost penalty, while grain or coal would be more limited.