Maybe more of a tip then a deal. This is just an example, lots of other opportunities without prime and with other games.
Got 8-10 hours spare over the next week to run through the Gears of War 4 campaign and not really interested in multiplayer?
1. Buy Gears of War 4 from amazon prime for £37.99
2. Sell the game at CEX for £36. You have 10 days to send it to them and keep that price.. https://uk.webuy.com/product.php?sku=0889842121513
3. Get the game the next day and keep the packaging.
4. Enjoy the game for a about a week, finish it? Keep checking back with CEX to see if the price holds, if it does you could cancel your old sale then resell and extend your time in affect.
5. Use the packaging to send the game back to CEX freepost via Royal Mail or Collect+
6. Only spend £1.99
Done this loads of times over the past couple of years without any issues. Play through all that latest releases with short campaigns for less than a fiver, if you have the time.
I assume you also get to keep the following games, not sure as I already have them.
Gears of War
Gears of War 2
Gears of War 3
Gears of War: Judgment