If you really are serious about being a design entrepreneur, then this book is worth reading. Luke Johnson is grew the Pizza Express chain from 12 restaurants to 250. He is also a chairman of the Royal Society of Arts and the former chairman of Channel 4. This book distills his knowledge and experience into one handy volume.
DJCAD graduate Joanna Montgomery has reviewed this book on her blog. As a successful entrepreneur herself, her views on the book are worth reading.