On demand when price equals zero

The City of Mesa Library allows patrons to check out CulturePasses—free tickets for a museum or other educational/cultural location. At first they just threw them all out there and let the patrons go on a feeding frenzy.

Then, beginning May 20th, they decided that they would put out a certain number at the beginning of each day, to ensure that everyone had an opportunity to get a CulturePass.

Now, beginning June 15th, they will put CulturePasses out at random times each day, again to ensure that everyone has an opportunity to get a CulturePass.

I predict that next, the library will allow each patron to enter a lottery for the CulturePasses.