It would be great to have a stackable kind of items, such as money or "credits". They might be placed into the inventory slots of the map, radio etc. They only require one slot and their amount is shown by an overlay number in a corner of that inventory slot. To remove a certain amount of that stack you might need to press shift plus mouse which opens a dialog to let you decide how many of them you want to take away.
Additionaly there should be these commands:
_unit addstack ["credits",245];
_unit removestack ["credits",102];