This is a deal alert, but only in the sense that the 200GB SanDisk microSD card has hit its lowest price yet. Instead of $220, it now goes for $200. That is less money than you would have spent two weeks ago for the same product.
That said, microSD cards in general aren't that expensive. You could get a 128GB card for $60. On a per-gigabyte basis, paying over three times as much for less than twice the data isn't really saving money.
So why splurge for the 200GB card? Well, it's convenient not to have to swap out memory, especially when the process involves taking off the back. That's just unpleasant. Is it annoying enough to justify an extra $140? Eh, that's up to you. There's always the option to wait a year and pay half as much, but by then, think about the 300GB you could be carrying around instead.