For the most part, UFC ticket sales are characterized by three stages: First, the vast majority of tickets that will be sold are sold by the end of the first day of the general on-sale. Second, there is a lull between that day and the serious build up to the show where very few tickets are sold, unless another big fight is announced. Third, they sell a lot of tickets in the final week with all the hype that gets people interested, and they sell tickets to tourists in Vegas as well.
By pricing average people out of buying tickets for their major events, the UFC has severely increased the importance of the first stage at the expense of the others. The only fans willing to pay 500 dollars for decent seats are super hardcore fans, and they all buy their tickets in the first week. It's one thing to get tourists to buy last minute tickets to an event if they cost 200 or 300 dollars, though even that is pushing it. It's another entirely to ask casual fans that get excited by an event due to the heat-up in the last week to pay $1,000 for a ticket. It just won't happen.
That brings us to UFC 91. In the midst of a financial meltdown, the UFC has priced tickets for this show higher than any ever before. They are also doing this in the city that has arguably been the hardest hit by economic stagnation in the last year. They can deny it now, but they were hoping to sell out this show by the end of this past weekend. They didn't come close. Sources indicate to Bloody Elbow that they have sold somewhere around 10,000 tickets (out of 15,000+). That sounds like a good number, but they won't sell any of the remaining $750 or $1,000 seats to casual fans, and the hardcore fans already bought.
In the end they will get an amazing gate for this show. They will probably sell it out with all the hype. But even if they do, they still have UFC 92 and UFC 93 coming up in the same city immediately after this show, on top of the TUF Finale. Something's gotta give, and limiting the experience of seeing the UFC live to high rollers and the most hardcore of fans is just not a good strategy for growing the sport or inspiring fan loyalty.
I originally thought they were doing this because of the rumored Rampage Jackson vs. Wanderlei Silva fight, a fight that would cost them millions due to the expected buyrate of this show. But that fight is still not signed for numerous reasons, and they may end up asking fans to pay $1,000 for Brock-Randy and Florian-Stevenson. We'll see how hardcore some of these fans really are if that is the case.
Update: According to Dave Meltzer they've only sold 7,500 which is a much worse number. The UFC does 80% of its ticket sales in the first week, so they better hope the way they hype it changes the metric.