before home depot and lowes took america by storm, there used to actually be a retail price and a contractors price at the supply house. contractors price was usually 50% of retail. It allowed you to simply buy at contractor, sell at retail. If the customer called the supply house, they were quoted retail. Actually, similar to what dnk said above.
unfortunately around here, the difference between contractors price and retail price at the supply house is negligble (sp?) And depending on the product, the HO or customer can sometimes buy it cheaper at HD or Lowes than we can at the supply house.
This project is probably way over budget. If it's been going on for two yrs at T&M, they are also over budget on the other trades as well. Now someone is being taken to task for this. Who is asking for the invoices? The owner or someone 3-4 notches down their totem pole? If it's the owner, you may be able to talk to him. If it's the underling, he will stop at nothing to save his boss money (and his butt a job)
So in a round about way, if you are in the postition to do it, take express quotes advice and talk with the manager/owner. Otherwise realize that the underling that is on you for this will be pretty zealous to prove to his boss that he can save them money (as short sighted as that savings may be) and realize that you will probably be off the job soon anyway. No need to give them any money back. Not much help, but hopefully the responses you get will clear things up.
good luck
