Interesting analysis. Do we know how the supply side affects prices as well?

My first campaign, I did not pay attention to this, but have been keeping an eye on them as well in my 2nd. It seems that all commodities have been consistently dropping in price every year, to the point that I assumed that they would eventually be worthless. I think though, that especially early on while trying to grow my trade revenue I prioritized building plantations & trade ports over weavers/workshops & infrastructure.

Is it safe to assume that for every plantation or fur trader you upgrade, you will see a small decrease in price due to increased supply? And that based on your findings, increasing town wealth will increase comodity prices across the board?

If this is the case, it seems one could reach this conclusion: that early in the game, your build priorities should be on town wealth vs. trade growth.