This is actually kind of interesting. The ending song was arranged fully and it's on the X3 disk in redbook audio (Which...well, used to be on TPH), but it wasn't put in the game for some reason. Instead, we get a cutscene with either a J-pop song in the Japanese version, or the song that you hear now which was on the PAL version.
As far as I know, the song is not on X Collection at all.
Personally, I kind of like the English X3 PSX ending.