1. A method for assembly of a web site for an online store of a seller, the method comprising: providing the seller with access to a warehouse of predefined products for selection by the seller for use in the assembly of the web site, each of the predefined products to be provided by a respective predefined merchant other than the seller, and wherein the access includes displaying images for each of the products for online viewing by the seller during assembly of the web site; receiving from the seller a selection from two or more transaction models to define an active transaction model for operation of the online store, at least one of the transaction models to specify customer order fulfillment by product delivery from the respective predefined merchant directly to the customer; and generating, by at least one server, one or more web site files for the online store that incorporate the selected predefined products and that are configured to perform transactions by customers of the online store using the active transaction model.