eBay has Call Of Duty: Modern Warfare for cheap, with the game currently going for $49 with free shipping.
The only catch is that you need to be an eBay Plus member (you can subscribe for free for 30 days then cancel if you choose to do so). You’ll need to buy it using the below links and the code PLUSPLAY
There’s only 100 per hour until 6pm tonight, but there seems to be a consistent flow of stock. The game is out on October 25th.