I saw this on another thread, https://forums.elementalgame.com/432847.  The basic thought is that the Sov. could have its own individual gildar storage for equipment purchase and then store costs could be more balanced against taxes income instead of the artificial inflation of prices to maintain balance of a sov getting to much too soon.

So you would have your normal Tax rate and then another rate of how much the Sov takes from that.  The higher the rate the sov takes the higher the unrest.  Think of it as another way to keep you from over taxing for the Sov's gain.  This also keeps the majority of the Gildar for buildings and soldiers.  The Sov can donate gildar to the tax office if the coffers are empty.  So the rate can go both ways.  This allows two different gildar scales to be used, then buildings troops being trained cost what they should without having to balance versus a Sov getting super powered from gear.

Obviously this needs fleshed out more, but just a thought.

My 2 Copper.