I had no idea that graduation ceremonies could be such a hot ticket (WSJ, subscription):
Jason Hughes, a senior at the College of Charleston in South Carolina, decided to skip his May 13 commencement ceremony. Instead, he sold one of his three tickets to a friend for $40 in gas money and auctioned off the other two for a combined $192.50 on eBay. "I'm taking what I learned about capitalism and applying it to life," Mr. Hughes says.
...Princeton University's student newspaper in April reported that students were trying to sell tickets for the June 5 commencement for prices typically between $70 and $100 each -- and ranging up to $250. The school responded the next day with an email warning to the class of 2007 from Tom Dunne, the associate dean of undergraduate students. "The University does not sell these tickets, and they are, strictly speaking, University property, not students' property," the email said. "Students who try to sell tickets, and students who buy them, are subject to disciplinary action." Says Cass Cliatt, a Princeton University spokeswoman: "Our interest is in making sure that every student can attend commencement, and there should not be a financial component to that."
I'm generally opposed to anti-scalping laws for sports and the arts, but in this case, non-price allocation of tickets may be in the University's best interest.
Update: The article is not clear on this point, but it appears that in many cases, tickets are rationed by schools on a per-student basis. Some students thus get a bundle of unwanted tickets, while others have a bundle of family members who want to attend the ceremony. A secondary market solves this problem, perhaps at much lower cost than any other method, given the initial allocation scheme. The high prices in the article are surely infra-marginal and likely stem from illiquidity. Would there be excess demand if schools charged $25 per ticket?