"but I'd like to make sure they go to people who'll appreciate it, actually turn up, can't afford to go otherwise and who'll get something from it."
You are trying to accomplish something you can't measure, except for the "showing up" part. The ticket is only part of the costs - there's airfare, hotel, etc, too. Keep it simple and raffle off the tickets. If it looks like only half the winners will show up, do another raffle. Anyone who wins AND shows up will have met most, if not all, of your criteria anyway.
YES there is! A non-profit company, started by a lawyer 47 years ago, will show you how to get pre-patent protection for ALL your ideas. Cost $495. Go here to learn more: www.inventions.org
You are trying to accomplish something you can't measure, except for the "showing up" part. The ticket is only part of the costs - there's airfare, hotel, etc, too. Keep it simple and raffle off the tickets. If it looks like only half the winners will show up, do another raffle. Anyone who wins AND shows up will have met most, if not all, of your criteria anyway.