@robinb @Minniekins and for those of you stuck with GS...
Retailmenot has a 20% off coupon with 2 or more pre-owned games (you have to open up the coupon in a private browser for a unique code for some weird reason). Both Battleborn and Doom are on sale at Gamestop (will come out to $21.19 + tax or $19.07 + tax with pro and coupon) and will trade in at $20 at BB. BB's trade in value went down since the beginning of this week, but you will maybe lose a dollar or so depending on your tax which is much better than selling your cards online.
You can trade in 3 max per system per title at BB. If you can find 3 of each game (3 battleborn xbox/3 battleborn ps4/3 Doom xbox/3 Doom PS4), you can move $240 easily with little loss. They have the availability of the preowned games on the app/website.