Bernstein Research analyst Toni Sacconaghi told clients in a note — as reported by “Fortune” — that Apple bought 23% of the world’s NAND flash memory last quarter and re-sold it to consumers for billions more than it paid.

The only difference between a 16GB iPhone 4S and the 32 GB model is 16GB of NAND flash memory, for which Apple charges customers US$100.
However, Sacconaghi says Apple buys that memory for a heavily discounted price of $0.67 per gigabyte, or a total of $10.72.

Read more at http://tech.fortune.cnn.com/2012/01/06/apple-bought-23-of-the-worlds-nand-flash-last-quarter/?source=yahoo_quote .