That's a pretty cool one there, Mel.
The one on Amazon is probably a fake, as it's described as 27"x42" and they have the "Wish you were Here" version, also at that size, which the real one is not.
The Spring Breakers "Wish you were Here" one sheet may also be some kind of "accidental" print, as I've only seen about a handful of them. It is kinda neat how there is cool artwork on the posters, and the fact that there are not many of them.