Howdy wsurfhead,
Thanks for using the Apple Support Communities!
I see you're wondering about the possibility of creating a shared calendar without having to be a Family Organizer and pay for all purchases. While Family Sharing does give you the option to use a shared calendar, it also makes it so the organizer will pay for all purchased content. To avoid this all you need to do is simply create a shared calendar instead of using Family Sharing:
iCloud: Share a calendar with others
Take care.