We’re expecting about 15-20 people with us in the park that day (that includes kids). I’m putting that expense on them. It is an expensive trip, but most of them intend on visiting at least one park, if not multiple parks, so they would be buying tickets anyway. For those that can’t afford the ticket, the welcome drinks, photo shoot, as well as (I forgot to mention this above) the farwell breakfast we’re doing gives people multiple opportunities to spend time with us for free/cheap.
I also think if you have guests that you feel might not be able to afford it, it’s cool to offer to help! You could pay for half of the day or offer to pick up the drinks/snacks while in the park- even a little something like that might help sway people towards going for it knowing you’re willing to help alleviate some of the cost! You could put a $25-50 gift card in a welcome bag that they can use to buy their ticket, or drinks, snacks, etc.