Looks legit to me.
The EPDG back is a mid-tier back, so there will be some premium for it being tougher than the most common backs -- especially because it is now posted on the main board.
One other thing to keep in mind regarding the Topps Buy Backs is that a former board member sliced them open to replace them with cards in worse condition or where he had erased a mark, etc:
http://www.net54baseball.com/showthread.php?t=243385
I don't worry about that here as he would have swapped this EPDG for a Piedmont or Sweet Cap card, but it reinforces Manny's comment that you shouldn't pay a premium for the Buy Back holder.