All of this theory is nice but completely useless in the real world ( game world in this case ). In my fellowship, we trade at 1:1 regardless of any other factors that would affect the cost of production. As long as the fellowship is properly balance, we don't need anybody else to get what goods we need. We encourage all members to produce only their boosted goods and to trade for the others. That way, we each produce more and gain an advantage from our own boosted goods. The system you presented might be applicable if we had different markets for neighbors, fellowship and others. If the markets where separated in such a way, different prices could emerge for the same goods where it would be possible to exploit the differences, but I doubt the game is going to go that way.