RedDeals is the best way to find great deals on the games you want.
Do you know reddit? Browse the GameDeals subreddit and add games to you wishlist.
You can also add wildcards as: online shop, sagas, publisher, special offers... (anyone said "humble bundle"?).
Whenever a sale matching your wishlist is posted to reddit, RedDeals will notify you, giving you the chance to go to the offer, view the post on reddit or dismiss it if you don't find it attractive.
Using http://www.giantbomb.com API
Icon by Gimpo Studio: https://dribbble.com/gimpo