There isn’t official pricing nor reliable sources out there so I’m going by rumors.

With your calculation you have to keep in mind that the Switch 2 cards have to somewhat match microSD Express speeds, so a more accurate comparison would be these, but they aren’t available in 64 GB sizes.

All I’ve heard is that they’re expensive and with the larger sizes often required for Switch 2 games it’s an even bigger problem than with Switch (1). These key cards exist for a reason. And I’d bet Nintendo takes a margin on these instead of only requiring the publisher to cover the manufacturing costs.