At a different level, there are various “recyclers” of books, physical media, some tech that use eBay as a channel to market alongside their own websites. e.g. Musicmagpie.
Typically paying a very small amount to buy the items from the customer, supplying a pre-paid parcel label and getting customer to pre-advise what is in the parcel, then stocking and reselling in as streamlined way as possible once receiving and assessing/refurbishing the stuff the customer sent.