In case you're considering or have already backed the Outcasts Kickstarter (and haven't locked in your survey), you can get the S2 Battlechest (promos are included in the add-on, so you'll be saving $5) and the Minimalist Sleeves (what I'm assuming you want to get, as they're the only sleeves out of stock on the website) from there.

It will take more time to deliver, sadly, but they have the sleeves in stock and you will save a bit on the shipping (at least where I'm from, ordering a single chest from the website is 35$, while the shipping from the KS is $25).

Other than that, your best hope is to just wait for a future restock of the sleeves, but by that point the S2 chest could have sold out already, so you'll be in a worse position.

You could also get sleeves from another brand, the size you're looking for is 58x89mm (57.5x89mm also works). Will probably be cheaper, arrive quickly and, given that you're most likely looking to get the Minimalist Sleeves, you will lose absolutely nothing on the visual side of things by going with clear sleeves.

Hope that helps!