I ran into this for the Treasure Island Music Festival. It cost $10 more to order online through TM than buy at the box office. This makes about as much sense to me as CDS financial transactions -- if TM wasn't a monopoly, no way this would be the status quo.
"Cracks are finally starting to form in Ticketmaster's money-encrusted shell, but the competition doesn't inspire confidence. Everyone looks at Ticketmaster's 30% surcharge and thinks how good all that undeserved cash would look in their pocket."