If you're ever in a pinch to save a few bucks kinguin is a great way to see if your favorite game is at a discounted price. Although I recommend linking PayPal with them I've seen Bioshock collections for $10, just recently I purchased Control for $6. The only recommendation I have is that you pay attention to the seller ratings, usually anything over 90% is a good buy and codes are generally delivered instantly to your account.
https://www.kinguin.net/
https://www.kinguin.net/