Why do text messages cost money while e-mails are free? Why do cereal packets keep getting smaller? Why do so many prices end in 9? In Priceless, bestselling author William Poundstone reveals how we perceive value and how businesses set the prices we pay. Rooted in the emerging field of behavioural decision theory, Poundstone reveals the secrets that multinationals - including Microsoft, Coca-Cola, Nestle, Nokia and Mercedes - are willing to pay millions for.