By Angus Grigg, the Business Reporting Team's Emilia Terzon, Elise Potaka and Ben Schneiders, ABC It's the Bunnings slogan everyone's heard - a promise to beat a competitor's price on the same stocked item by 10 per cent. But there's a catch to the hardware giant's famous price guarantee. While Coles and Woolworths have been under intense scrutiny, Bunnings - which has a much higher profit margin than either of them - has mostly escaped attention.