"Between $800 and $900 million is lost in business in the United States every Friday the 13th. A businessman in Guangzhou, China, recently bid 54,000 yuan (almost seven times the country's per capita annual income) for a lucky license plate containing the sequence 888. Continental Airlines recently advertised an $888 flight to Beijing with the slogan "Lucky You," and the Beijing Olympics are scheduled to open on August 8, 2008 at 8 p.m.
In another study of American college students at an East Coast university, the researchers found that having participants think about Friday the 13th made them significantly more risk averse. Participants were told they were participating in two unrelated studies. After thinking about Friday the 13th or a neutral day (Tuesday the 19th), participants were then asked to make a choice in betting situations, for example a guaranteed $18 or a 20 percent chance to win $240. Those who had thought about Friday the 13th chose the safe option 49 percent of the time, versus only 35 percent of those who had thought about a neutral day."
Medical News Today, 16 Feb 2008
Of course 900 million dollars is a small price to pay for a little innocent superstition.
It would be interesting to know what religion itself costs.