I was reading a interesting thread on Anandtech where someone estimated the cost of a GF100 die based on it's size, the number of dies that could fit on a wafer, the cost per wafer, and TSMC's current yields. He estimated that you would get ~90 functional Cypress or ~38 functional GF100 dies per wafer with Cypress costing $78 per die and Fermi costing $184 per die.
When you factor in the profit margins ATI and Nvidia would like to make per chip Cypress would sell for $170 while Fermi would cost $370. This is just for the gpu and doesn't include the cost of any of the other components on the card or the OEM and Retailers profit margins.
Here is the source
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