A method may include receiving, from users, information identifying items purchased by the users, the information including a price for each of the items, and storing the information in a database. The method may also include receiving, from a second number of users, additional information identifying items purchased by the second users, the additional information including a price for each of the items, and identifying a first item in the database that matches a second item associated with purchases by one of the second users. The method may further include determining whether the price for the second item is lower than the price for the first item stored in the database and updating the database to include the second price for the first item, in response to determining that the second price is lower than the first price.