You can use "My Price Guru" feature to keep track of the best deals.

"My Price Guru" works by keeping tabs on the lowest fares available for your favourite destinations. You will need to nominate these favourite destinations in your Yahoo! Travel profile.

Once you've done this, you will be able to view these great fares on the Home Page whenever you access Yahoo! Travel as well as request for alerts whenever the fares go below your specified fare value.