I'd respond with

Thank you for your inquiry. While I'm unable to accept a ticket to your event as payment for services I'm happy to provide a quote for you and a payment plan once we've discussed the project requirements. Let me know if you'd like to meet or call regarding this project.

I'd respond with something similar to:

Thank you for your inquiry. While I'm unable to accept a ticket to your event as payment for services I'm happy to provide a quote for you and a payment plan once we've discussed the project requirements. Let me know when you'd like to meet or call regarding this project.