So like I say with any braking system good small parts are important. In this case pads and rotors would be the main thing (and potentially hydro hose but if you have good quality brakes as you do that is usually less of an issue than with cable stuff) Cheap rotors are never worth it unless in an absolute emergency and that is all they have. Get good rotors, it sounds like the shop has rotors at a decent price. Yes there is cheaper stuff there is almost always cheaper crap out there some of it legit some it fake but doesn't matter it is crap. My favored rotors for Shimano brakes or 1.8mm needing brakes would be the IceTech rotors from Shimano they work really well and are worth the price. It is in comparison to a new braking system a low cost item that can greatly improve braking that and some good pads (I like Kool Stop or SwissStop generally) If you are trying to just go cheap then avoid at the very least resin only rotors.