That's consignment selling, not a trade in. Meaning the shop never takes ownership, but that shop expects a profit for storage costs and having the consignment item in view of the public.

In my line of work, a trade-in value is going to be maybe as high as 40% of what an item might sell for if the item is in good shape, still desirable, and needs next to nothing to make it sellable. Of course the value of the trade may be higher on paper if the item being traded into is fairly expensive and has a high enough profit margin to eat some of that trade in "value". Essentially just moving numbers around to give some more discount on MSRP.