There are none.
I suppose that for scholarships, something like that could someday be possible. I once heard of a model where somebody wanted to go, but couldn't go, so they said "I'll buy the ticket if somebody will take lots of pictures and tell me all about it!" I could see facilitating such an arrangement if the pictures and stories were all posted at permies. So this sounds like something scholarship-ish. But I suppose we wait until somebody offers to fund the scholarship and then we offer it.
I remember being involved in an event a long time ago .... the event allowed sliding scale. Out of a hundred people, apparently I was one of two people that paid the full $100, while everybody else at the event paid the reduced $70. I felt like I was subjected to a sucker tax. Ever since then, I did not like sliding scale stuff. So I won't offer it. And I even tend to shy away from events with it.
I remember that there was an event where a bunch of people were splitting the proceeds at the end because they all worked very hard to make the event happen. And one of the leaders allowed a few friends in for free (sort of like "instant scholarship"). The other leaders resented that they didn't call up friends in advance and offer the same thing. When I heard of it, my position was that the leader in question
should have opened his wallet and bought tickets for his friends.
I've been in events where they thought it was good that the event offer a couple of scholarships. They would go to people that are broke and have too little time to do work trade. Like maybe a single mom. My thought was that if they have too little time to do work trade, then they probably don't have time to attend the event. And what about all of the other single mom's that pulled off paying for the event? Doesn't it seem disrespectful to them? And, on top of that , when the scholarships are offered, there is a deluge of people asking for the scholarship! Somebody now has to fish through all of those applications and decide who to give it to. Plus, there just seems to be something that takes away a person's dignity in having them beg for a ticket.
