While I haven’t seen any examples of group buying in the US, there are groups in Japan (Auto Group Buy), China (Teambuy, Taobao, Liba), and Malaysia (Tumpang) who have implemented it. Very simply: groups of consumers pledge to buy or put a deposit down for products that are then bought in bulk and sold to the individuals at a discount. It works a bit differently in China, the sites mentioned facilitate “tuangou” by connecting consumers online who want to buy the same product. They then all meet at a store and negotiate for a mass group purchase at a discount, on the spot.
It seems to make the most sense for slower, big ticket items such as the specialty auto parts at Auto Group Buy, as opposed to the lower priced items on Tumpang. Do you really want to wait months while enough orders are collected for you to finally get your briefcase? Still, it’s a cool idea and anyone can post an item that they can procure in bulk for below retail.