The storage available as standard inside the Nintendo Switch is tiny compared to other games consoles at just 32GB. But due to the use of cartridges for games, if you buy physical copies then internal storage isn't going to be an issue. Digital purchases, however, will fill up that 32GB quickly, so a Micro SD card is essential.
Unlike Sony, which forced expensive proprietary memory cards on to PS Vita owners, Nintendo opted for the Micro SD standard. These cards are cheap and readily available worldwide, but that doesn't mean Nintendo isn't keen to make some cash from sales of the cards.
With that in mind, accessory manufacturer Hori is set to launch a range of Nintendo Switch-branded Micro SD cards. They'll have the Switch name across the top of the card in white on a red background. They are fast Class 10 cards and will initially be available in 16GB and 32GB sizes launching on March 3 in Japan alongside the Switch. Both cards are already listed on Amazon Japan without a price.
I suspect we'll get the same branded cards in the US and across Europe. I also don't think it will take long for a 64GB card to appear. Typically, you can expect to pay $10 for a 16GB card and $13 for a 32GB card. If I had to guess, I'd say Hori will offer these branded versions for $15 and $25 respectively, or even $20 and $30 considering Nintendo will demand a percentage of the profits on every card sold.
If they do turn out to be that expensive, then do not buy one. There is no difference to a standard Class 10 card other than branding. Also, consider that a 64GB Micro SD card can be had for under $20.