I think it might just be an error on their page. They've been updating it ever since the day it got announced bit by bit.
I went on this afternoon and the main product page was live but you couldn't order through that, so I searched it, in the results I clicked "Buy" and it worked (doesn't work now though...)
Keep checking though. I suspect it's just an error...surely they'd make more Joker steelbooks, right?
Edit:
Here is where I get taken to from my order history. Incorrect URL perhaps?
Also note, the CE version is no longer listed in search results either...