[Ekaros]

It really wasn't any more scarce than let's say wheat. And price seems to have been around same level with wheat take or leave some depending on distance from production.

What really made it special was that it was commodity with possibly limited production locations, that kept extremely well and was in steady demand. So it is one thing that everyone uses and is relatively easy to tax. And the price likely was much more stable compared to food and other goods.

The large scale demand also lead to it being desirable as military target, once you control the production you are good.