Is there a website where I can go to see when normal retailers have had sales in the past, so that I might predict the arrival of the next one? Better yet, ima

Is there a website where I can go to see when normal retailers have had sales in the past, so that I might predict the arrival of the next one? Better yet, imagine this data set: the price of every consumer good sold in retail stores, as a function of store and time. What would be the impact of such a database, if it became widely available, say, from a company whose mission is to organize the world‘s information and make it universally accessible and useful?