I estimate how many man-hours it's going to take. In other words if the job is going to take me 4 man-hours than I would charge 4 times my hourly wage (x). Then for transporting goods I charge at the rate of $x.xx/mile (y). I would then find the distance that the truck would be traveling from shop to work site to dump site back to shop. Then I would charge per cubic yard of debris (z).
I would turn around and reply that it would cost him/her: