In recognition that within 50 yards about the only differences between heavy and light charges are noise and recoil, we're doing almost all our range shooting with our small game light loads. Those are 20 grains in 32, 25 grains in 36, 35 grains in both 50 and 54, and 40 grains in 58. We also recover and recast all our balls. Sure there's energy cost for the recasting, but that's no different than casting from new lead. I don't know if energy figures into your ball costs, but if not, our balls are free.
Using your #'s, that means we're spending .05 for the 32, .06 for the 36, .09 for both the 50 and 54, and .09 as well for the 58. I agree that patch costs are negligible because we cut our own from ticking and make rather than buy our lube. Sure we'll pump up the loads for big game hunting, but that's a pretty minimal quantity of shots compared to small game and range shooting. Therefore we're spending roughly half (.05 vs .09) to shoot our small bores.