I wonder if I could please get some advice from more experienced members of the community. I have had a engine built and some other work done on one of my cars which required a lot of parts (New year ratios, webers, etc). Most of the invoice was parts (which didn't surprise me). The bill however, was significantly more than I expected and when I checked some of the parts online the prices looked high although it was difficult to find real comparison on the majority of the parts as they were just listed generically. I haven't spent a lot of time on it, but on one part I could source 30% cheaper. The well known specialist did admit that the parts were marked up to reflect the time sourcing them but this one was an error and he would credit it back. He has thus far however not disclosed the mark ups on other items. I find this hugely opaque. Is this normal? I am based in the UK. I might be naive but I had always assumed that parts were supplied at cost and specialists made their money on labour? (Which is also a sizable amount, at £70 an hour).