Distribution business model

Dear All ,

I have a question , I want to bear only distribution cost of 16% .

I will buy item at zero price , and I will sell the item lets say at 100$.

16% of 100$ = 16$ is the distribution cost , which will remian with us .

rest 84% of 100$ we have to pay back to the supplier .

it means cogs should be 84$ .

and I want to automate it in the system ,in such a way that extended cost should be automatically updated to 84$.

Thank You