A low cost, and a "first come, first serve" system seems to reasonably favor those who have a genuine interest in attending. I'm sure there's probably better systems for that, but neither of your suggestions seems to accomplish the goal of distributing a limited resource (tickets) to those who would get the most benefit from them.
A minimal barrier to entry (say, a $10 ticket) weeds out those who have lots of time, but no real interest in attending - otherwise the tickets would probably routinely get wasted by those who snagged them for free, but had low odds of actually attending the event.
A high barrier to entry (say, $200 per ticket) weeds out those who have low income, regardless of their interest in attending.
A random lottery doesn't favor anyone, and thus those who are going for a whim have equal chances to those who have been dying to see The Really Good Band Reunion Tour ever since they heard about it in 2005.
Off the top of my head: $200 per ticket, free tickets if you have low income and fill appropriately annoying paperwork as a barrier to entry. (Or the latter only regardless of income.) Or a random lottery plus scalping (those who don't want to attend all that much selling to hardcore fans).
Scalpers want to avoid finding themselves with unsold tickets. (Though maybe they don't, if it makes sold tickets much more expensive.) If it frequently happens then scalping benefits neither scalper nor customer, so there's a paternalistic reason to ban it.
Edit: Actually, scratch that - sell tickets and the right to resell them separately.
Recent brainstorming sessions at SIAI (with participants including Anna, Carl, Jasen, Divia, Will, Amy Willey, and Andrew Critch) have started to produce lists of rationality skills that we could potentially try to teach (at Rationality Boot Camp, at Less Wrong meetups, or similar venues). We've also been trying to break those skills down to the 5-second level (step 2) and come up with ideas for exercises that might teach them (step 3) although we haven't actually composed those exercises yet (step 4, where the actual work takes place).
The bulk of this post will mainly go into the comments, which I'll try to keep to the following format: A top-level comment is a major or minor skill to teach; upvote this comment if you think this skill should get priority in teaching. Sub-level comments describe 5-second subskills that go into this skill, and then third-level comments are ideas for exercises which could potentially train that 5-second skill. If anyone actually went to the work of composing a specific exercise people could run through, that would go to the fourth-level of commenting, I guess. For some major practicable arts with a known standard learning format like "Improv" or "Acting", I'll put the exercise at the top and guesses at which skills it might teach below. (And any plain old replies can go at any level.)
I probably won't be able to get to all of what we brainstormed today, so here's a PNG of the Freemind map that I generated during our session.