Earlier quoted context omitted.
Certainly, see for example https://aws.amazon.com/ec2/reserved-instances/ , search for "Scale with your Business". Similar discounts exist for most of their other services.
I remember reading something about how AWS is pretty much running very close to at cost (super razor-thin margins, just like the Amazon shops themselves),but seeing these numbers seems to imply otherwise (20% is a big chunk of change).
It is predicted that Amazon AWS runs at a huge margin [2]
Of course it's possible that these number are skewed by some Irish Whiskey Double Dutch Vegemite Sandwich tax avoidance system.
[1] http://venturebeat.com/2013/10/24/red-is-the-new-green-for-a...
[2] http://venturebeat.com/2013/09/05/amazons-mountain-of-margin...