Good evening James and welcome to the Events Calendar Support forum!
First off, I would like to apologize for the delay answering.
We are currently experiencing a higher level of requests than usual.
Please rest assured that we are working hard at correcting this situation.
We appreciate your patience while we try to normalize things.
Thank you for reaching out to us.
I would love to help you with this topic.
The best way to achieve what you are looking for would be using a code snippet.
You can apply the following snippet in the functions.php file of your theme (without the PHP tag at the top) as a starting point: https://gist.github.com/GeoffEW/69f8a033fb614c78b3de45a197431135
What this will do is display whatever value you input in the event cost field and disregard the ticket prices.
Let me know how that goes.
Best regards,
Geoff B.