What is up with Amazon sellers who list a used book at $600 when the next is $15, yet still have excellent ratings?
Usually with that much of a spread, it’s intentional. For various reasons, it can be easier to change the price of an item than to remove the listing. In some cases sellers set outrageous prices on their inventory to mark to themselves that it has been sold. Then the items are returned, and the inventory is back up, but they have not yet looked at the pricing.
There is another breed of seller that is doing some sort of drop-shipping arbitrage on a wide scale. These guys basically list a massive inventory of titles they can order from other sources.
Another potential is the use of repricing software. Bad source data or faulty algorithm design is a common cause for seemingly illogical listings.
Keep in mind — price on Amazon has nothing to do with the seller’s ratings. An Amazon seller can offer thousands of products for exorbitant prices, but their feedback is based upon past actual completed transactions and whether they were delivered on time and as promised.