Sometimes that may be from the store owner's collection.
The local chain here had a ton of Sega heavy hitters (Master System, CD, etc) come in all at once and it turned out an employee had "traded them in". I would assume he got a much better cash offer than usual.
A different store in that chain had somebody that must have dumped off an inherited Wii collection. Tons of random underpriced rarities that I snagged, so I can only imagine what I missed.
Haven't been to any of those stores in a few months, but next time I go I'll see what (horribly overpriced most likely) expensive stuff is behind the counter for you there OP.