Can I buy the Black Spirit Pass?

You can't see the Black Spirit Pass anywhere else, but it's not for sale, right?

 

I do understand your question (I think), it is just the way the sentence has been put together that is confusing me.

Did you know, that you can make a Search in the Pearlstore?

I suggest that you do that, and remember to do it in all the categories, before giving up.
I personally bought it in the Pearlstore, so I know it Was in there.

 

At the moment it's limited to the webshop only.

 

As @foxywarrior pointed out, Black Spirit Pass is available at Pearl Shop only at the first week of the Season, after that you may bought it on Web Shop.