I have just recently joined Wild Apricot and several of us are now testing our system.  I have administrative access to both our Wild Apricot account as well as our Paypal Account.  One person registered for an event and selected to pay online.  She went to paypal and forgot her paypal information so aborted at that point.  ...

Not sure what you refer to as 'payment page' but I suspect this would not be possible.