Do tickets have to be purchased on line or can they be purchased at the station prior to the departure time. Also are rates higher on weekends?

Tickets must be purchased at the station prior to departure. You can go to the attendant or the kiosk. There is also an app or website you can use at https://gobrightline.com. Keep in mind that they don't accept cash at all, even if you go to the station. Rates vary depending on time and day.

Rates increase with demand, so generally prices are higher during rush hour on weekdays. Weekend prices generally are low but may increase if there is a sporting event, festival, etc.

You can purchase both online and at the station