Exemplary methods, apparatuses, and systems receive a browsing request to view an item offered by a first third party retailer. An estimated inventory value for the item at the first third-party retailer is retrieved. The estimated inventory value is maintained using a combination of a history of purchases of the item and a history of inventory values for the item received from one or more third party retailers. A representation of the item as being available for purchase is transmitted to a user device based upon the estimated inventory value for the item. In response to receiving a request to initiate a purchase of the item, a request for a current inventory value for the item is transmitted to a retail server. The purchase of the item is initiated in response to determining the item is available based upon the received current inventory value.