Group buys happen a lot of the (Audi) Quattro World forums for example. A member comes up with an idea, runs it past a vendor, and posts a notice - say, group

Group buys happen a lot of the (Audi) Quattro World forums for example. A member comes up with an idea, runs it past a vendor, and posts a notice - say, group buy for 10 sets of wheels. People respond by placing pre-orders with the vendor. Once the minimum is reached they turn into orders at the pre-arranged discount and shipped out. Could even be a generic service to facilitate these kinds of deals through arbitrary small vendors.