Sometimes caravans come through and offer you a one time deal. I think it would be interesting if you could setup a trade agreement for basic items.
Say you setup your town away from possible stone resources, when the stone merchant comes by you could set an automatic trade agreement with him for specific items (Of which, you could set your people to automatically fabricate). In exchange you would get the resources you might be lacking at regular intervals.
This would work well to keep your crafting citizens busier, especially after the initial usefulness of what they currently make is exhausted (Like, for me I usually turn my stone maker into a blacksmith in the beginning to save on Hearthlings)
Other interest with this might come to the end of the agreement when it comes time to renegotiate your trade deal.