Interesting theories.
However they don't seem to take into account that purchasing second hand equipment doesn't seem to effect the weather as badly as purchasing new equipment. I believe you need to include and adjustment factor somewhere in your calculations to take this into account. Not having done a direct comparison on the effects of new versus old I believe as a starting point a simple ratio of old to new would give a valid starting point. eg C_O_E/C_N_E . (cost of old equipment/cost of new equipment)
So Octanes oiginal equation would read
W = sqrt(C * (E_u / E_p))*C_O_E/C_N_E