I gues one node represents one developement step in CMOS;

http://en.wikipedia.org/wiki/International_Technology_Roadmap_for_Semiconductors

• 45 nm – 2008
• 32 nm – 2010
• 22 nm – 2012
• 14 nm – 2014
• 10 nm – 2016
• 7 nm – 2018
• 5 nm – 2020

so 3-4 nodes means we are 6-8 years ahead, 10-14 nm compared to 45 nm.
Imagine how much investment Si-companies spent in R&D and equipment to reach from 45 to 10 nm??? I guess about 20 billion USD!