The trader game on EC simply doesn't exist right now. The only way to go is lord/steward, and just buy whatever you can, and then resell to know buyers later. The free market will only work with large numbers of both buy and sell, and traders that have significantly longer range than lords.
...and I believe the only way that is likely to happen naturally is if there is a large area of the map that is chronically short on food, but rich, and another area of the map, of comparable size, that is chronically short on gold, but has plenty of food surplus.
Not only does that not happen given our current maps, any realm in the former area would fall apart due to starvation before the food would be likely to be brokered to them, and any realm in the latter area would not have enough money or nobles to withstand assault by a richer realm that wants the breadbasket for itself.
