http://www.youtube.com/watch?v=95CQAjsIi3k

So I found this absolutely gorgeous piano solo version of Last Regrets on youtube. However I can't seem to track down who wrote it or what album/single it was released on. It does say 'Kanon AIR Piano Arrange Album ~Re-feel~' in the clip but really it's not on there. A transcription would be very much appreciated but even just finding out where it was originally from would make me very happy.

Here is the link to the sheet music while I was searching around on the Internet. ^.^ I don't know whether or not they are accurate, but I go to this site frequently.
http://josh.agarrado.net/music/anime/index.php?searchterms=kanon&srctype=

I'm afraid the one you posted is not the accurate sheet music for the version the OP posted. Of course, from the looks of it, I think it's the one from Re-Feel, so it should be a good transcription to use if one wishes to.

I highly doubt that you're going to be able to get a sheet music of that on the net; it sounds like a personal arrangement to me; it'd sounds like a pain in the ass to have that written down. Of course, I'd be wrong.

Basically: The above version is not right, it's unlikely to find the sheet music for it on the web, most likely you'll need to get someone to transcribe for you if you want it.

Aah, all right. ^.^" Well, I tried . . .

I believe josh's transcription of last regrets is from Woody Rinn's "Piano de Kanon" album (like most of his other kanon transcriptions). There is no last regrets track on the Re-Feel album (not the one I know at least) and I don't think there is any other official piano instrumental versions of the song. So that leads me to believe that this is either a fan made arrangement or from a doujin album of sorts.

Ah, yes, my mistake. You are absolutely correct. There is no Last Regrets in the Re-Feel album. Yes, the version on Josh Agarrado's site is from Piano de Kanon album.

In any case, if you would like, I could transcribe this version of the song for you, but due to my inefficiency and lack of experience with music notation software (Finale 2011, the one I use at the very least), and time issues will put me an ETA of approximately one month.

Frankly, I don't have much an experience with direct transcribing such as this either, but I could try.