Turbot,
This idea has been posted before, and is a good idea, 
however a major flaw is when there are 
100 bishes 115 knits 49 rooks.... rooks get the big discount, but 
knits and rooks are hammering bishes.  In reality its 
164 rooks/knits vs 100 bishes.
  This could lead to strategic country swapping.
  A better idea thats along the same lines is..a perk cost 
multiplier could be the number of bases a particular 
country has.   For example, if rooks are down to 
4 bases, thier multiplier would be 4.  If they 
had 30 bases it would be 30.
ex.  B*V=PC,  where B is number of bases,  V is a global 
                      set value for that particular plane and PC is
                      the calculated perk cost.
So when one country is getting hammered, they would be 
launching 262's at a cost of, say, 30 perks, while the hammering 
country may be costing 360 for the same plane.
  I dont think this would effect the ultimate outcome, 
but it would make getting ones bellybutton kicked, a whole lot 
funner
