How do I get the deadeye armor?

Games Other Halo
1

I have recently seen the deadeye armor online and I really want the armor but I have no clue on how to get it

2

Dead Eye was a Best Buy preorder. I believe the only way to get it now is by buying off eBay or the Halo 4 Goty edition. Not to sure about the Halo 4 GotY