Hold onto your butts, as Jurassic Park era Samuel L. Jackson would say - the following offer is of the hot and spicy variety. Gamestop will sell you GTA 5 for a mere £4.97 when you trade in two selected Xbox 360 titles.
Games covered by the offer extend from the great - Forza Horizon, Metro: Last Light, Rayman Origins - to the not-so-great - Madagascar 3: The Video Game, Fist of the North Star Ken's Rage 2 and Apache Air Assault. If you were fool enough to buy any of the latter, rejoice, for your foolery has paid off.
[Update - As OXM contributor Ben Borthwick notes, GTA 5 itself features on the list of potential trade-ins. That's some impressive proof-reading right there, not that I'm in a position to judge.]