For every Olympic games, there are Olympic pins. For collectors, the buying, trading and selling of them is  as competitive a sport as any beach volleyball game, and it’s been going on since 1896. The pin trade, an obsession for some, is labeled the “unofficial Olympic sport.” In Beijing, pin sellers have set up shop at the Olympic Expo in the Beijing Exposition Center and in the Coca-Cola sponsored pin-sales center. There are new pins and old ones from previous games, common pins that are handed out by sponsors to anyone and more valuable pins, such as those given to athletes and officials. Most pins are inexpensive - $4 to $10. Now you can join the frenzy by getting some Beijing pins. A page on the Beijing site gives the history of the pin frenzy and describes the “pindemonium” going on there now. The official U.S. Olympic Shop has an assortment of pins for sale, such as a ceramic Beijing logo pin or a YingYing mascot pin, each for $7. NBC’s Olympic online shop has pins, like a gymnastics mascot pin for $8 (pictured) and a rickshaw pin for $6. The Olympin Collector’s Club site has lots of advice and pin facts: there’s even a club member blogging from Beijing. After the official sites, you’ll have to turn to pin-selling retailers, such as Greekshops.com, Collectpins.com (where a USA/China flag Beijing pin is running $8.95), Discountpinstore (they’ve got a set of opening and closing ceremony pins for a pricey $24.89) and Athenspincollection, where you can find individual sports pins, such as a soccer pin for $8.95. When the games end, start looking on Craig’s List and eBay for the special pin you covet.