Reddit mentions of Ultra Pro 40ct Black Oversized Deck Protectors 82420

UltraPro makes oversized sleeves. They fit the big Commander cards and the big Planechase planar cards.

https://www.amazon.com/Ultra-Pro-Oversized-Protectors-82420/dp/B003K5TMJW/

How big are Cosmic Encounter race cards?

Magic: The Gathering oversize sleeves can accommodate 3" x 5.5".

http://www.amazon.com/Oversized-Deck-Protector-Sleeves-40ct/dp/B003K5TMJW

Another option is to go ahead and laminate them. I think Staples sells laminating kits.

http://www.staples.com/Laminating-Service/product_381713

I bought it at release for $100 from my LGS (and am very satisfied), so $76 is insane value - with the money you saved, you can get some sleeves (link is for 80, you'll need an extra pack of 40) and a box for them.

Alternatively, if you prefer toploading sleeves, Ultimate Guard makes them, but they're a little more expensive when you factor in shipping. Personally, the sideloading sleeves work fine, but if the toploaders were available before I bought the sideloaders, I would have bought the Ultimate Guards.

Sleeves: https://www.amazon.com/Ultra-Pro-Oversized-Protectors-82420/dp/B003K5TMJW

Binder page: https://www.amazon.com/20-Twenty-Pages-4-Pocket-pockets/dp/B004QVH0RK

They do exist - yes. Its however up to you to find the best deal on them, this is just a quick google search I Did.

At the moment, your options are largely limited to this (edit: and the other boxes linked in the comments below) for deck boxes and this for card sleeves. You'll note that all of these are Ultra Pro products, and none of them are particularly desirable. I would be very happy if KMC or similar got into the oversized card market - niche as it may be - in response to the renewed interest in Planechase.

Yes they do.

They do make oversized card sleeves. You could even back the two individual cards with an oversized card from, say, the Commander precons so it doesn't get all floppy.

I haven't measured them myself but I believe, they are 3.5 x 5 in. If so, these should fit them:

Ultra Pro Oversized Protectors

I use Yugioh sleeves like these - http://www.amazon.com/Ultra-Supplies-YUGIOH-Protector-Sleeves/dp/B004R7DUZ4 . They're a little big, but they work well enough. They are a bit slippery, so it does limit the max safe height of the draw decks.

And then for Dungeons/Caverns/Hideouts I think it's these - http://www.amazon.com/Oversized-Deck-Protector-Sleeves-40ct/dp/B003K5TMJW . They are oversized Magic the Gathering sleeves.