It's more instructive to think of the Web distribution channel as having close to zero MARGINAL costs. If you have an Amazon-scale infrastructure, and you incr

It's more instructive to think of the Web distribution channel as having close to zero MARGINAL costs. If you have an Amazon-scale infrastructure, and you increase your physical book shipments by 10%, you need to cut down 10% more trees, hire close to 10% more guys in the warehouse, pay 10% more to UPS, etc. For e-books, increasing shipments 10% increases the costs of the salary, infrastructure, etc. probably less than 0.1%.