Like other agents, Cssbuy sells items that have been abandoned at the warehouse for more than 180 days. They call it the "Cssbuy Wholesale House". These items have usually been forgotten and have no flaws. They are in new condition and greatly discounted.
Cssbuy advertises a 30% discount, but it seems like in reality it's mostly 50%. That's far less than Superbuy's 75%-90%.
The page also features items from sellers, so it's not only warehouse stock, that might explain the higher prices.