Can strongly recommend https://www.reuter.de/
I am usually all for buy local but the selection is exceptional and prices are significantly lower than buying here or NI.
Transport is usually quick and uncomplicated, and reasonably priced.
Even with the transport costs added stuff is still very much cheaper than buying here. Of course, if you order more stuff at the same time you can always make some savings there.
Not sure if its in your 'gotcha' category but I've mentioned before on AAM about builder's providers and neighbours warning about not to buy Cooke and Lewis bathroom suites (B&Q) because parts are different sizes.