Limiting buyable iron?
Afaik, this would have a few consequences:
- Iron would effectively go back to being a limited resource, thus more valuable
- Because of the previous point Crossbowmen would become more valuable, since they are easier to keep alive and retreat with from a losing battle than melee iron warriors
- Axe Fighters and Scouts would also become more used, since they can function without iron
- We could still use the Market to buy the odd iron item without building the whole production chain (which iirc was the reason the Market was introduced in the first place)