I have always charged for my certification and markup of the chemicals. If they studied the materials, took the test and paid the outrageous insurance cost of buying storing and spraying, then they could buy the chemical at .0055 cents/acre. Just my philosophy.
The cost of my hours is what I charge for my time, that I am using to be there and not at some other job.
The mileage seems self-explanatory.
If I should drop the cost of my chemicals to 1 penny per acre I can see that, if it is the only way to land a bigger contract. but selling it at cost seems off to me.