The diseased mind of a used game outlet. You have 10 copies of a game. Rather than price them at $20 each, price them at $90 each. That ONE person a year who might actually pay what you're asking makes it so worth it.
And this is why these stores are overstocked on unwanted copies of Final Fantasy VII at $60 or more apiece, when they could make a fortune selling them for $20.
I'm surprised Hitgaming is still around. Does ANYONE pay those prices? But selling on Amazon means no store rental or overhead, just it and wait.