CNN Headline Shirts?

I have found the new "shirt" option at CNN.com to be one of the most unusual innovations I have seen recently. For a given news link from the homepage, there may be an icon of a t-shirt, which if you click on looks something like this. They look like little more than an advertisement for CNN, and if you continue to the shopping cart, they cost about $15. This feature begs the following questions from me:

1. How do they determine which headlines get the shirt option? I suspect an algorithm is behind it, but I want to know the parameters.
2. Who buys these shirts and why? A while ago I saw a headline that read something like "Repeated sex offender accidentally released from prison" which carried the t-shirt option. I wondered who they thought would want to wear that around town.
3. The marginal cost of the link to buying the shirt is probably near zero, so why not provide it for every article?

I place a prior probability of 0.80 that I will one day buy one of these shirts. The prior is just 0.50 that it will be before the end of the calender year.