I saw that, too. I was surprised as Best Buy usually doesn't overcharge for games like that. Usually it's Gamestop and their "Nintendo tax."
Even the normal 'Nintendo tax' is like $5, though, which is why this caught me totally off guard. I can only figure that it's a screw-up and they categorized it with 3DS games. Or, the conspiracy theory version, which is that they figured if people pay $40 for a 3DS game, they'll pay $40 for this.
The only consolation is that I knew enough to catch it. I'd imagine there will be people that don't even bat an eye.