This is a great writeup. I think comparing average revenue to average cost would be better served as a stacked area graph rather than superimposing them, since

This is a great writeup. I think comparing average revenue to average cost would be better served as a stacked area graph rather than superimposing them, since your method makes it look like average costs actually shrinks to a very small amount (when its just that the gap between the two figures is shrinking.)