I know I'm late here but I just found out about the black market today. Where have I been? I have to thank @DrewTowers909 for making me aware of these mysterious packs!
In case you live under a rock like I apparently do, here is how to access the black market. Go to the Packs/Buy Packs menu and simply set aside your controller for the next 30 minutes. Do not navigate out of that menu. After 30 minutes press the back button. You'll automatically gain access to the black market.
Currently in the black market you can purchase up to three diamond infinity contract cards for 15K VC each and/or up to three Throwback Super Packs at 18,750 VC each.
Diamond Contract Cards and Throwback Super Packs in Black Market
