Just my opinion, but I would say charging for the consumables is reasonable. You'll pay for them one way or the other, and the fact he is being so transparent with his costing seems to be a good thing to me, rather than a bad one.
If you are really bothered, you could ask him for all the blunt bits and snapped blades at the end of the job, but I'd let it go if I were you.
If you are really bothered, you could ask him for all the blunt bits and snapped blades at the end of the job, but I'd let it go if I were you.