Hello Chelsea,
You can use the service fee option. First, turn on service fee under Event Details / General / Event Configuration and under Event Details / Prices/ Services Fee you can create your own service fee name and price. This can be applied to invitee, guest or both. You can set the price by amount or percentage and even select a registration type to charge.
#Flex-Creating/ManagingEventsHope that helps
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James Rose | Senior Web Developer and Content Management
Digital Infrastructure, Implementation, Strategy, and Support
Office of University Development | University of Michigan
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