A self-checkout system, comprising: - a base station (25, 26) for communicating with a number of display devices, and - at least one display device, designed as an electronic price display tag, which comprises + a storage stage for storing a product data record (PD1-PD3), which was received during communication with a base station (25, 26) via a first wireless interface of the display device, and + a second wireless interface for communication, particularly for RFID or NFC communication, with a self-checkout device, + wherein the display device is designed for processing a self-checkout query received from a self-checkout device for the purpose of transmitting the product data record via the second wireless interface, and - an inventory management system server, where the connection between a product, which is assigned to a display device, and the display device is known, wherein - the display device is designed for receiving and storing user and/or device identification data for identifying the user of the self-checkout device and/or the self-checkout device during the processing of a self-checkout query, and wherein - the display device is designed to transmit only the identification data, for which an approval of a user of the self-checkout device for carrying out a payment transaction for the said product data record is present, to the base station (25, 26) and from there to the inventory management system server, wherein - the inventory management system server is designed to forward a product identifier, particularly the product data record, together with the identification data to an external internet-based search engine, which had previously been contacted by the self-checkout device with a search query and the identification data of the self-checkout device and stored the search query and the identification data, so that the information gap between the search query for a product or the search result and the actual product purchase can be closed at the search engine by means of the feedback of the display device. - a base station (25, 26) for communicating with a number of display devices, and - at least one display device, designed as an electronic price display tag, which comprises + a storage stage for storing a product data record (PD1-PD3), which was received during communication with a base station (25, 26) via a first wireless interface of the display device, and + a second wireless interface for communication, particularly for RFID or NFC communication, with a self-checkout device, + wherein the display device is designed for processing a self-checkout query received from a self-checkout device for the purpose of transmitting the product data record via the second wireless interface, and + a storage stage for storing a product data record (PD1-PD3), which was received during communication with a base station (25, 26) via a first wireless interface of the display device, and + a second wireless interface for communication, particularly for RFID or NFC communication, with a self-checkout device, + wherein the display device is designed for processing a self-checkout query received from a self-checkout device for the purpose of transmitting the product data record via the second wireless interface, and - an inventory management system server, where the connection between a product, which is assigned to a display device, and the display device is known, wherein - the display device is designed for receiving and storing user and/or device identification data for identifying the user of the self-checkout device and/or the self-checkout device during the processing of a self-checkout query, and wherein - the display device is designed to transmit only the identification data, for which an approval of a user of the self-checkout device for carrying out a payment transaction for the said product data record is present, to the base station (25, 26) and from there to the inventory management system server, wherein - the inventory management system server is designed to forward a product identifier, particularly the product data record, together with the identification data to an external internet-based search engine, which had previously been contacted by the self-checkout device with a search query and the identification data of the self-checkout device and stored the search query and the identification data, so that the information gap between the search query for a product or the search result and the actual product purchase can be closed at the search engine by means of the feedback of the display device.