I agree to having certain prices listed, such as a base price for installation, but I'm doing a price list you must always inform that prices may vary according to the job. Example would be , changing a faucet in a 1 year old house where the lines and cut off valves are new, probably won't need to be replaced as apposed to a 30 year old house that the faucet never been replaced, will probably need new field lines and cut off valves. So listing prices can be good for certain jobs as a base , but needs to be determines by the situation