Don't know about that. "Retail" customers and handymen make me think residential.
If you are doing T&M the customer should know up front what your hourly rates are and how they are computed. I know some companies that fax over an authorization to the customer that explains the rates they will be charged. It must be signed by an owner or other person with authority and faxed back before any work can start. That way there there should be no surprises.
Flat rate they have the entire cost up front so I can't see what they would complain about. If you are there for 1/2 hour and give them a flat rate bill for $900 you should already have justified it- again get it in writing.
Anybody customer that takes the time to research material prices to argue with me or asks for the prices I pay my supplier is an insult to my intelligence. As I said I have zero tolerance for that practice and the relationship with that customer will end right there.
-Hal
