Hi,
Thanks for using our plugins. I can help you out here.
When using the ticketing plugins such as WooCommerce Tickets it hides and replaces the Event Cost Section with the ticketing.
The plugin then uses the Ticket costs to display as the cost field of the site.
If you like to add it back please look at this ticket:
https://theeventscalendar.com/support/forums/topic/event-cost-disappeared/
And here is a direct link to the snippet that ticket refrences:
http://pastebin.com/AjVd8bH2
Let me know if that works for you.
Thanks