I think I would rather buy the part and install it myself, then have some know it all young adult do it.
My LBS has 3 mechanics, 2 in the back working on the drop off's and one guy up front that helps the walks in and does sales. He'll do quick air ups or set up a Tubeless tire, dropped chain, etc and shoot the crap with you as he does it. They also do an summer apprenticeship with some local kids to teach them the in's and out of bike repair.