A number of sets of methods and apparatuses applicable to online shopping are disclosed. One set, “Bin Packing Methods with Approximate Membership”, includes methods in pricing and auctioning a bundle of items, some of which could belong to another bundle. Significantly, the membership of a bundle, during pricing and auction, could change. Another set, the “Shopping Console”, puts a structure into the online shopping experience, so that through one interface various shopping activities can be facilitated, including but not limited to researching, pricing, negotiation, group buying, and tracking of purchases. Still another set, “Flash Mob Shopping”, allows sellers and a (spontaneous) group of shoppers to connect on prices without requiring shoppers' hard commitments, and with sellers revealing only necessary price information.