There are 3 ways you can create an IBAN/BIC payment for a Eurozone seller 
 

1. Have your own Eurozone Euro account (unlikely for most USA ebayers) 
2. Via your own bank, who will initiate an International  Transfer for you (for a fee of $20 - $40 or more)
3. Use a trusted third party  service that can make the IBAN/BIC transfer on your behalf, 

(There are no USA banks with an online IBAN/BIC transfer function to a Euro account)

For information on a trusted third party service to make IBAN/BIC payment for you, please visit my About Me page