Commercial Websites

They offer little choice in materials (profiles, paints, etc.), but are very reactive about new products. It’s not the least expensive, but often interesting promotions.
Artisanal company devoted to the manufacture and sale of very high quality spare parts (wheels, tracks, etc.). The website also offers many uncommon tools, Swiss quality, and reasonably priced.
My favourite online store in Germany, with prices often lower than in France, especially on German or Austrian brands. The fees are usually very reasonable (e.g. €3.90 since 2017 for an order of more than €100).