The large-scale table salt trade involved a terrifying amount of great silver coins.
Kant sold 400 bags of fine white salt at a price of 100 great silver coins per bag. In other words, it was a total of 40,000 great silver coins. Those merchants would have to use rattan baskets and carts to transport the great silver coins.
If they used goods, they would not be able to match the profits of table salt.
Other than spices, military supplies, or sweet sugar cubes, the other things were not worth the profits of salt at all.
No matter how good the iron, cloth, and farm tools were, they were all dispensable goods to the fine white salt with stunning profits. Although Kant did need it, and the merchants would prepare some in order to please Kant, they definitely would not prepare too much. If they prepared too much, they would only be able to exchange a bag of refined white salt for a full cart of goods.