Yeah, why not, They have a HP bonus Box which isn't even used, why not have a Unit upkeep modifier too. You currently have a Unit cost in Government which can be changed, and a Unit Requires support Flag, but If you set the government cost to 2, I'd liek to be able to make some units cost Nothing, -1 normal, Normal or +1 normal, only problem I can see, If your in a government where units dont cost, and a unit has -1 cost, then this unit will 'give' you cash
Actually I think at the moment that the current costing is 'added' up and you pay for the 'troops' not pay individually..
Also I'd like to see a 'food' cost, or even a 'troop effect' where some troops have +/- food/ent/tax/happines