The problem though, JST, is that the current 'population model' really sucks from the point of view of unit costs. In fact, the 'population model' also really sucks for plague and bombardment effects. If they could only change this model then people WOULD be able to simply mod population costs into their game as they see fit. Of course, this still would NOT change my argument for variable gold 'upkeep costs'-thats just a 'no-brainer' IMHO!
Oh and , as I said in my above posts, one way to offset the higher costs of modern high-tech units is by allowing a civ to be in a 'lower readiness' level. There could be 3-5 readiness levels with normal being the 'default', obviously. There would then be either 1-2 higher readiness levels, and 1-2 lower readiness levels. High-readiness improves combat ability for your troops, but at greater maintainance cost, wheras low-readiness reduces costs, but gives your units a penalty in combat (making you prone to sneak attacks!)
Yours,
Aussie_Lurker.