Gamestop has their 4/$20 and 4/$40 sales on pre-owned games going again both online and in store. Games must be under $10 to qualify for the 4/$20 and under $20 to qualify for the 4/$40.
With some games (Callisto Protocol for PS5, for example) it would be better to buy them new as they’re cheaper new than pre-owned. In this example it’s $3.75 new versus $14.99 pre-owned.
4/$20(Sorted high to low, but not by console): https://www.gamestop.co
4/$40(Sorted high to low, but not by console): https://www.gamestop.co