Use the Charge Event feature to accept payment for an Event without registering any specific seats.
For example, you might use this as a deposit for a private Event.
On the Event page, click More Options > Charge Event.
On the Charge Event page, enter the name in the Customer Information section.
Under the Payment section, enter the Amount and the Payment Type.
Clicking Credit Card as the Payment Type will open a Billing Information form where you can enter the credit card information.