Steam is my preferred way of buying computer games. Not boxes cluttering your house, and you won’t have to hunt around for the discs when you need to reinstall.
If you haven’t heard about Steam, then you won’t have played any games by Valve in the last decade.
Never pay full price on Steam. They have lots of sales, but keep tracking would be a fulltime job.
You can get Steam to let you know when a game is on sale, by adding the game to your wish list.
Once you’ve done that, go into your “Email Preferences” and make sure “Send me an email when: A discount is applied to an item on my wishlist.” is ticked.