I buy very few games, as I don't get a lot of time to play. I tend to try a game out before I even think about buying it... $50 is too much to drop on something that you might absolutely hate. I have COD4 and have only played it a few times. It didn't hurt me to buy it, though, as I got a Wal-Mart gift card from work and used it to buy it... didn't actually cost me a dime.
If I want a game after i have gave it a test drive, I will usually pick it up at Wal-Mart. The price is as good or better than any other retailer, and I can take it home and install it right then. I don't buy downloads of games unless it is an ISO of it.