I really try not to give anyone any guess. Seems like anything you say a number they keep that figure in the back of their heads then when you are over that amount then you look bad even if there has been extra work needed. I just say I keep an excel program going with every paint material and other parts/materials I use and log my hours. Only thing I have not figured out to cost out and should is items like welding gas,wire,sand paper,fillers,tape,paper,wax/grease remover. I keep up todate on costs on primers to clears. I figure it out my cost and mark up per ready to spray oz. that way when I use say 20 oz of surfacer I can log that amount. Kinda ałso gives people ideas on what each thing costs. Been pretty handy.