It is worth whatever an unopened pack of tennis e-reader is worth, no more, no less.
I work in a production facility. Machines goof up, operators goof off. Stuff goes out all the time upside down, backwards, etc. Most of it gets past the quality control and goes to the customer and usually no complaints will come back unless the product is damaged or drfective.
This is a packaging error, nothing more and should not be compared to mis-struck coins, reversed stamps or error baseball cards!