No, it's not the cheapest price this game has ever been. But it's currently the cheapest option if you're thinking of snapping it up for Christmas. With most retailers sitting pretty around £30, it would appear Tesco are doing the same...until you add the game to your basket that is. Then it drops to £25 quid.
As a number of eagle-eyed HUKD-ers have noted superbly, this'll work for Mario Kart 7, Mario Tennis Open, and a handful of other 3DS titles too. Again, thanks to loll1es @ HUKD for the initial spot.