Re: Apprentice Shadow Pack - Where
It would be in the cartel Market screen under packs if it is still available. If it's not there then the pack has been removed from the market and is no longer for purchase.
They do occasionally bring back older packs for sale but there is no telling when that will be. If it's not in the Cartel Market the only other place to purchase any would be ones sold on the in-game GTN however the prices will vary depending on what they are being sold for and how many are available.
From what I can tell that pack was released back in Feb 2015 so more then likely it is not on the cartel market unless they bring it back for a short sale but as mentioned no telling when that would be.
