Upkeep will be governed by the following rules:- 1. The base unit for upkeep is an infantry unit, at 10S per turn 2. When a unit levels it adds half its base upkeep, for example a level 9 piker = (10 + 5*8) = 50 schmuckers per turn 3. Warlords upkeep is 10 times that of an equivalent levelled unit, for example Jillian, a level 9 warlord (10+5*8)*10 = 500 schmuckers per turn 4. "Templates" such as Heavy, Flying etc can be added to a unit for an increase in upkeep. 5. If you have provisions, upkeep is reduced by 70% rounded up.
As stated elsewhere in canon, a warlords purse is level * 1000.