I think it's less that it's an "extended version", but more that the album version is an edit of the original (which is the "C.A.U.B. version). I actually have put that version in place of the album version in my iTunes library. Don't think it is available anywhere other than on the Party Hard single though.

Just gone and ordered the single after finding it's only £2 on Amazon, which I feel is well worth what's on the disc. Strange that it's so hard to track down on the Internet (besides illegally downloading the thing).
P.S. I must ask if you're the same LeoVK who did the theme tune to Jim Sterling's "That Videogame Show What I've Done"? I was watching an episode today and I swear I saw that name come up in the credits.

That's really cool! I'm a big fan of Jim's work. I vaguely remember him mentioning you when talking about "Scumbag College" on an old episode of Podtoid (though I could be mixing this up with someone else). Definitely a small world.