An electronic person-to-person double auction-like system that facilitates trade in many differs sorts of item via the World Wide Web or similar such interface. A plurality of sellers can post details of items for sale, including a minimum bid amount and buy price for each. A buyer can create a bid basket comprising bids in respect of a plurality of heterogeneous items available for sale, together with bid-withdrawal rules defining circumstances in which respective bid(s) are to be withdrawn. Bids are binding unless withdrawn. The auction for any item continues until a buyer posts the buy price therefor or the seller accepts a bid posted therefor.