In reply to Miroslav Glavić.

They definitely are, and I can see a case for levels of ticket prices—but I also see that as potentially problematic for those at the lower end of the income, particularly students and starting freelancers, who are probably the folks we most need to attract.
Maybe we should be considering ticket costs as “minimum admission; if you can do more to help support, please do” with an explanation of the needs both at the low-income individual level and at the organizers’ event-planning level.