Amazon said Friday it would buy Whole Foods Market for $13.7 billion as the giant internet retailer makes a deeper push into the grocery space. From a report: Amazon has dabbled in brick-and-mortar operations, experimenting with a bookstore that opened in New York last month and plans to open "no-checkout" convenience stores. But the Whole Foods acquisition represents a dramatic departure from its early business model founded on online retailing and related technology. Grocery retail is a notoriously thin-profit-margin business. And Whole Foods -- often derided as "Whole Paycheck" -- has struggled in recent years to keep up with emerging competitors that are expanding nationwide with cheaper items. Traditional grocery stores have also widened their organic food selections in hopes of retaining customers who are increasingly looking to eat healthily.