That sort of change (ie running parallel economic systems) would probably require two instances of an economy mod running different data files.. one with limited stock disabled; with unlimited stock, and player to player trade disabled and where the balance can only be increased by donating - it would be a major change in the business logic of the mod as a whole. For my servers if i was to add donator perks I was thinking more giving them extra trade zone slots or increasing their bank balance based on their donation amount.. and maybe stocking up their player owned trade zone stock.