Yes Roger has made several posts on this issue. I agree maintaining ships sholud cost something, but how much?
We could have increasing costs as the ships age (discounting 50-75% refits which would restore the vessel to new)
We could simualte costs by frequent small refits (5-15% cost)
We could use the above scheme but if it took half of our points/tonnage each qaurter then smaller navies would be trapped with small navies, there would be no incentive to build others would lay up ships to avoid paying and in wartime costs may be massive.
I do not agree with including wages, after all we then would have to pay for spares, manpower both on ships and ashore, ammo, aircraft etc and fuel. How many nations here have enough oil for their fleets? How much is imported and at what cost.
IP and materials are produce of the economy, not expenditures taxes would pay for wages etc. We can't sim this and we could open a can of worms here, a complex can at that. I'm all for realism but we just have to ignore some things.
Just my thoughts on this issue, if someone comes up with a workable and simple plan then we could vote on it.