Bidding on a plurality of items with contingencies. Input may be received from a buyer over a wide area network. The input may specify a plurality of offers for purchase of a respective plurality of items and the offers may be included in a collection of offers. One or more contingencies may be associated with the collection of offers, e.g., in response to user input. The one or more contingencies may specify cancellation of one or more of the plurality of offers within the collection of offers. Input may be received from a seller over the wide area network, specifying an acceptance of a first offer of the plurality of offers in the collection of offers. At least one of the plurality of offers within the collection of offers may be automatically canceled based on the one or more contingencies and possibly the acceptance of the first offer.