GameFly offers used copies of Star Wars: Battlefront for PlayStation 4 or Xbox One for $18.99 with free shipping. That's a buck below our mention from three weeks ago and $13 under the lowest total price we could find for a new physical copy elsewhere.
Rush Hour Whole Saler via eBay offers used copies of Halo 5: Guardians for Xbox One for $19.99 with free shipping. (GameFly has it for the same price with free shipping.) That's $11 under our mention of a new copy from last week and the lowest total price we've seen in any condition. (It's $10 below the best deal we could find for a new one now.)