What can be annoying, though, is when the shop declares that its overhead multiplier is driven by the same supplies they then charge customers for directly. Seen it, done it.That is the way mechanics do it. But as a former repair tech 40 years ago, I agree with it. Those supplies are expensive and when used, if you do it properly you use quite a bit. For example DeOxit, use it liberally and it works very well. Brake cleaner? Same way. The customer should pay for it though as it involves a job well done and not just slopped together and left all nasty and dirty. Just IMHO.
Rick "once upon a time a professional mechanic" Denney