As far as PC processors, Intel sells approx 200m units per year (50m or more per quarter). So the R&D $$/unit are approx $30/ea for Intel. (and $50/unit for AMD).
For every processor, Intel sells about 1.5 chipset components, so add in another 300 million units for a total of 500 million units. Now we're down to $12 per unit. Then there are lots of other product lines as well.
Thanks for the correction... that number sounds more reasonable... I should have double checked. Both companies have products besides just CPU that consume R&D dollars, but I think CPU is the revenue generator that fuels the company. --Alan