The core product is what matters, but shouldn’t complimentary extras be taken into account, like the original box, and instruction manual? Should you accept these extras as missing for the same value as an identical twin with these extras? Absolutely not.
But guess what? GameStop, and other retailers are guilty of not offering a price difference between complete, used products, and incomplete, used products. This is unacceptable in wake of the price difference of new, and used products. Frankly I’m surprised that this has hardly been brought up before.