Online ticket brokers such as StubHub.com have been around long enough that they are a standard ticket buying or selling experience for many fans.

Can’t make a game – stick the tix on StubHub. Need tix for a game – grab them off StubHub.

The model is brilliant. They charge the seller 15% commission, and then they charge the buyer a 15% tax as well. Say you post 2 tickets for $50 ea, so $100 total. The buyer sees a price of $57.50 each and pays $115, with StubHub taking the extra $15. Then StubHub sends you a check for $85, keeping the extra $15. That’s a 30% commission on 2 tickets changing hands. But the program is still the easiest marketplace around.

But there’s an interesting next level to this marketplace. How do the sellers decide when to post and how much to offer?

This Thursday and Saturday, the NCAA West Regional will be in Anaheim, CA. Two of the participants, San Diego St and Arizona have large alumni bases within driving distance. The Arena holds 14,000 people and is officially sold out. On Monday morning, the lowest ticket price on StubHub was about $225 and there were about 790 tickets.

Since then, the number of available tickets has fallen to between 450-500, but never lower. Meanwhile, the price has dipped into the $150’s. So while theoretically the supply is falling, so is the price.

So who is keeping the supply set at around 500? How many tickets are actually being moved? It looks like StubHub is automatically dropping the prices by a certain % every few hours. Then when old tickets get purchased, new ones are getting posted by the brokers. That way there’s never a listed supply that encourages people to keep waiting. The incentive is to jump on the listed price before the supply dwindles more.

So I wonder if it’s StubHub limiting supply, or the brokers themselves. Based on its 15% x 2 commission model, StubHub certainly has the incentive to keep prices as high as possible. But it also has incentive to make sure all the tickets get sold. So somewhere is a Pareto optimal equation for StubHub that isn’t necessarily optimal for buyers and sellers.

I assume they don’t open up their API’s, otherwise someone would have built the “Farecast for StubHub” by now. Until they do, all you can do is keep an eye on it yourself.