I am thinking of the following for Avian Knights:
1: Resources are required to manufacture goods. Each good has different requirements.
2: Resources can be supplied from the region, from the skyland (Internal trade), or from other skylands.
3: Trade routes and trading partners can be set up between skylands, though these are not permanent - even setting aside war, the skylands are at the mercy of the wind, and trade routes can just get unwieldy. When a trade route is broken, a new source must be found.
4: Skyland to skyland trade routes heavily influence relations between skylands.
This should establish a trading game based not on ferrying goods from place to place, a la Traveller, but on exploration and diplomacy.