Depending on where you travel from, there are variour airlines traveling to the San Francisco area for a docounted price. The cheapest airline is Norwegian.
www.norwegian.com ~it is recommended to book as early as possible to get the best deals! However they have good deals shorter before as well :) there is a 24 hour open purchase.
Other good airlines:
and many more!
Good search engines are:
It all depends on where you will travel from.
It is best if you can arrive in Sacramento. San Francisco will also work, but from there you will need to take an airport transfer to Sacramento Airport where we'll be picked up!