How much would you charge for a haunted house if proceeds go to charity?

So the company i work for is teaming up with a local sports team to put on a fall festival/haunted house for Halloween. All proceeds will go to 2 charities. So profits have to be split in 2. I think $10 for adults is totally reasonable to charge someone. While my coworker says it should be $5 or $8 cause it’s the first year of the event & shit. I really disagree with that considering we’d raise way less money, particularly cause the profits have to be divided. & the research I’ve done shows that most haunted houses across the country avg at $15. Thoughts?