Old, discontinued games sometimes stay at a price like that at EB.
As a former EB manager, my guess would be that $50.99 is the games cost, and EB guesses that everytually *someone* will buy the two they have left, so they don't have to lose $45 per game.
If a B&M has it, it will be the same price, but they are usually just kept in a small stack in the back. My store had this at $50,99 and mario 64 too, for an equally wierd $46.99. We never sold them... I mean you'd have to be retarded to buy the new one for $50 when the PO one is only $10.