I used to have this problem with my supply house. The price I paid on any item would vary with the counter guy I was dealing with. When I finished a large commercial job a few years ago I sorted through all of my invoices on the job and found I had paid as little as $1.38 and as much as $2.45 for the same Hubbell 5352 duplex receptacle on the same job. I sat down with the branch manager and he set my account up on a set margin so no matter who ran a ticket for me I was paying a set margin for materials. I told him I wanted him to make money but I needed consistancy from him so I could make money too. I think if you pursue this with your supplier from this viewpoint you'll find it to be a communication problem they are willing to correct. It's in everyone's best interest.
