More information about tickets can be had at the When, Where, Fees page and the FAQ.
Before you buy: we recommend reading the Team Levels information so you know which level is right for your group.
If you haven't already done so, you can also sign up for the San Francisco Treasure Hunts email list here to make sure you receive notice about hunt dates, registration particulars, ticket sales, advance clues, etc.
(and don't forget to check the check the hints page for pre-hunt teasers and... hints).