Until February 12th, the 3DS will be discounted $20 to the $149.99, just a few days before a certain Sony handheld is released as a First Edition Bundle. Of course, you could just get both the 3DS and Vita. (*gasp* Blasphemy!) Other people think this is just a way for Nintendo to clear their stock of 3DSs to make room for the 3DSi Lite XL... or something.
With the extra $20, though, you can get a Circle Pro Pad Accessory. Or just take it out of the price of a great game, like Resident Evil: Revelations or Super Mario 3D Land.