Are you the only consultant who could figure out how to bring down the cost of the appliance (in the articles example) down by 1$?
If not then your value is not as high as you used in the calculation. The potential client could find other consultants to do the same thing (price optimization of a mass product - service well available in the market). As there are more providers then estimating the "value" should take in to account that there are several offerers of service. It is now a tendering situation. I am now excluding a remote situation where all the offerers of the optimization service would collude in their offers.