Systems and methods for a network-based sales system with customizable user interfaces are described. The system generates first and second sales interfaces based on customization commands and communicates the sales interfaces, over a network, through respective member sites to first and second users. The system further receives first and second requests to view a listing of an item that is presented in an offer for sale via the first and second sales interfaces, retrieves a record from a central database system that is changed responsive to a sale of the item that is presented in the first and second sales listings, modifies an object model representation of a central database system based on the retrieval of the record that is changed and regenerates the first and second sales interfaces responsive to the modification of the object model representation.