Look at the brightside. You only spent 99 cents for the backing track. If you like the backing track's music over the Legends music, you can always swap out the mp3 files and hope the graphics match up. Downloads from select a track are usually only about 3 dollars and you can download them immediately after paying for them, just like on i-tunes. BTW the song is not on SC8406 according to KJPro, just Brick 5 as far as SC discs.
I've downloaded a song from i-tunes to make a karaoke track and then realized I already had the song on CDG by a different artist than the one I was thinking about and the music was close enough where I didn't really need to create my own karaoke file. Another 99 cents shot to hell.
Bookmark the download sites that have been suggested. They have lots of songs that you can get one at a time instead of buying an entire disc for the ONE song that you really want. It takes quite a bit of time to create a "GOOD" karaoke track from an i-tunes mp3 file. For an extra couple of bucks, it's usually better to just buy the pre made tracks from Select A Track or a site like it.
One more thing...before you say a song can't be found ANYWHERE; at least check out KJPro.com and look through their data base first.
http://www.kjpro.com/browse/