Crap, sorry, I just realized the Kindle version says not currently available.
Looks like the Kobo source should work though, or at least there's a "buy" button (though I've never bought from Kobo, maybe they wait until after you click "buy" to tell you it's not available or something like that).
And while it's listed on Apple, I can't find a "buy" button. Not sure how apple works, maybe I'd need iTunes installed to get it.
Anyway, here's the links...
Also, I'll PM you if none of these work.