You buy batches from bankruptcies or merchants and sell them directly on Marketplaces such as Bol.com and Amazon. A webshop is less or irrelevant. The products are often already known on for example Bol.com, so you only provide your stock, delivery time and sales price.
You are now ready to scale up to multiple marketplaces; possibly also marketplaces where your products are currently not offered yet. However, this will take a lot of time and energy. Do you recognize yourself in this situation? Did you start on marketplaces or do you mainly sell on marketplaces and less on your webshop (s)?