(Purchase using the actual 3DS unit in the online eShop - I couldn't find a webpage link to buy it outside the DS environment, sorry.)
So if you're like me and been living under a rock the past decade and just bought your first DS ever in the Amazon sales last week, then this could be the deal for you.
I've looked and I'm pretty certain this is the cheapest it's been. It's discounted for a New Years sale.