Also, in direct response to the Gp, grocery stores buy sales data that contains their sales + their direct competitors down to the product level. It is anonymoized but freely available.
Edit: Also companies like Google scan emails for information. Amazon stopped including prices in their emails because Google was getting a direction stream of sales data with full costing info.
Edit: Also companies like Google scan emails for information. Amazon stopped including prices in their emails because Google was getting a direction stream of sales data with full costing info.