I don't see that the expansion is available for sale-am I missing something?
Crisis is for sale, although it tends to be sold out a lot. I picked up a copy of base game and all the Crisis packs a while back. It can be a lot of fun to play and is easily learned.
I have only one set (and all Crisis packs) so I haven't experienced the 4 player variant yet but 2 player is fun enough.
The digital version for PC and tablets, base game only, also has quite a few people playing it. There are two options there, one with five minutes per turn, and one with 72 hours per turn for when you just want a leisurely strategy game.
There's another expansion (Gambit), but I'm not too sure what that is. The site has little information on it and I can only find conflicting data. It's either the Kickstarter bonus, a tournament set, or both... I'm not getting it for now at least. Last I heard Gambit would get an official release some time in 2015.
The creators tweeted yesterday that Crisis has been printed again and should be shipping, so by the holidays hopefully more packs will be available everywhere ☺