Hey Rob!
Good question. Unfortunately, ticket sales for Eventbrite have to take place on Eventbrite.com. We would love to keep the entire purchase experience in WordPress, but there are some limitations to the Eventbrite API that prevent that from happening–there are good reasons for that, too.
If you want to keep event purchases on your site, then the best way would be to use a WordPress ecommerce platform, like WooCommerce. We have an add-on for it that allows you to create tickets for events, which then displays them on the event page and handles the transaction completely through WooCommerce.
Sorry, I know this probably isn’t the answer you are hoping for, but does it at least help? Please let me know!
Geoff