For years, retailers like Target Corp. and Wal-Mart Stores Inc. were dogged by the question of what to do about Amazon.com - match its prices, or risk losing customers to the online giant? They appear to have made up their minds. It cited a study by Wells Fargo and market researcher 360 pi that tracked 100,000 products over the past year and found that Minneapolis-based Target beat Amazon's prices by 5 percent on average; in August, Wal-Mart undercut Amazon by 10 percent.