Its depend on your event. What kind of your event, but Event management companies also have packages.
What Do Event Planners Charge?
I used to work part-time in an event management company. In case of fundraisers, the charges are a bit low. The best event planner will charge approx. 25% of the total cost. The average will cost around 10% of the total cost. And the total cost/budget/donation is in your hands.