You can't simply go to the My Nintendo Store and buy the Switch 2. To order the Switch 2, you need to log in with an active, paid Nintendo Switch Online account. Once you do that, you can choose either a Switch 2 standalone console or the Mario Kart World bundle and then hit the confirm button to "register your interest" in ordering a Switch 2.

Sam's Club: The Walmart-owned warehouse club had the Nintendo Switch 2 Mario Kart World Bundle on June 5. It will only be available to Sam's Club members. New members can get an annual Sam's Club membership for $25 (was $50).