On jobs like these I keep everything as simple as possible:
First, I add the price for materials (including sales tax, if applicable). But while getting all the materials, it is still as if I am on the job - thus however long it takes to get all the stuff is multiplied by my hourly wage (yours may be $40, $50, $60, etc.). This goes against your conventional markup but my hourly rate is used as that is the basis to generate revenue.
This sum is added to the time (hours) I estimate for the job.
Posted via Mobile Device