I had assumed that the way it would work would be sorta like, the towns will automatically do the process where they take in a raw resource, make it into a goods, and then use it. With the prices in a npc only line being basically meaningless, since it's the town paying the town and it just takes it's own money. But the prices being important when a player takes part in the line, that the town will buy goods for 5, and that workshops will buy resources for 2 (and sell for 5 if the trader wants to move the goods to a town that they own things in so that town can make stuff) and that player workshops can buy goods for 2 from whatever npc resource gathering infrastructure exists then sell it for 5 (or best of all probably, the player making resources, then making them into goods, then selling them for five in pure profit)
Although the questions I have, do players need to pay for the goods that their infrastructure uses, or does the town pick up that cost (thus making it profitable to just sell to yourself to extract money from the town...) and can you selectively give goods to infrastructure (such as your own infrastructure) for free if there isn't enough money/goods in town to keep them running?