If a local shop orders parts from lets say shimano it must be bought from the official shimano importer. All while the online shops import it themselves and undercut the prices by a lot.
I once wanted to buy a new bearing for the crankset and my bike was already disassembled. So i went to the local shop to avoid waiting for shipment (was before next/same day delivery was a thing in germany). The price there was about 50 or 60€ while the online price was something in the 20th. I talked to the owner what the reason for that big of a difference and he showed me his official B2B catalogue. It was basically the price he asked for. So he wouldn't even make money out of it if I would have bought it there. He recommended to just buy it online which I then did.