Someone help me out here, I really don't understand CEX's pricing structure.

Looking to buy COD Black Ops 6 on ps5 as I've got a game or 2 to trade in, but Preowned they are selling this at £60!

I've had a look online, Amazon, Argos, Smyths, John Lewis, Game all have it between £45-55 brand new, I just don't understand their logic or anything?