If I am correct I heard in the live streams that trading will be done with gold as ‘money’. I have the idea that direct trade fits more into the setting.
You trade your abundant goods with the trader and get other goods in return. Of course goods will still have a value on them similar to gold, but it can be hidden.
For example you want 5 stone from the trader and offer 5 grain in return. The trader then says something like: “I need more for the stone” or “That deal sounds fine” or “You are generous sir”. And can offer something in return. Similar to the system in Civilization.
Goods can be valued according to their rarity for the specific trader. Stone has less value to mountain-people then grain for example.
It can also create some nice situations. You want some rare stone from an exotic trader. But he does not want your abundant grain, cause he has already enough grain. Do you offer him your rare goods, or do you go steal his grain and make him willing to trade for your grain. But if he detects that you stole from him he likes you less and as a result you have to offer more goods to him.