1)Go to Best buy..
2)BUY THE GAME.
3)Open the BOX
4)Write down the CD KEY
5)Return the game and get a gift Certificate
6) Repeat steps 1-6 for every game you ever wanted!
7) you can always download the ISO from warez or torrents. Just need the cd key to play on legit servers.
Also I hope you are not changing the CD KEY by reinstalling every time. You can simply Change it in the registry.