Geoffrey,

I see your point.

I did not mean in any way that Galic/nomadic peoples were "poor", rather that, let's say, the "central government" had less monetarized budget than the Greek or Roman ones, relying rather on solidarity networks for collective action such as warfare.

Given the abstract nature of the EB system, this relative ease of access to what is comprised within the scope of these solidarity networks ("vassal" tribes' soldiers...), compared to what is outside (Greek mercenaries...), could be modeled, IMO, by a relative lower upkeep for faction MIC troops in the case of factions relying on such government systems.

I see the limits of this proposition: in the case of profesionnal warriors, who certainly existed as you mention, my suggestion is self-deceiving, I admit.