Maybe it's not only the game, maybe this is part of a larger plot, the buyer knows that inside that plastic cover, waiting since 1998 there's a hidden document that will prove to be very important in the near future, the buys knows it is this specific copy due to the serial number on the box!
So..... treasure map? Medievil 3 art work? Oooh :O
"We's afraid the Master of the house is out at the moment trying to plunge the land into eternal night,
but come on in, and make yourself at home" - Zarok's Entrance Hall Gargoyle