The Autographs and Photo-Ops at Anime Matsuri are devided in two categories.
Unlimited
These Guests have booths in the Exhibit Hall and are available to meet fans for extended periods of time (Usually during openign hours of the Exhibit Hall). For this type of session, you can pay directly at the Guest’s booth
Limited
These Guests do not have booths. Their Autographs and Photo-ops are scheduled and access to them are only done through pre-bought tickets. These Autograph tickets usually go on sale about 2-3 months before the convention.
Don’t forget to check the Autograph and Photo policies