@Following on from Leo's point without the figures direct from the developer there's no certain way of knowing.
Developing high profile games will vary in cost depending on developer , some are better and more efficient with the money they receive others not so much , we also have to take into consideration that many technologies will be shared between development studios (namely Sony ) which will reduce the cost's.
"Q: When I visited the London Studio recently, everyone was keen to stress that there is a new spirit of collaboration between Sony’s in-house development teams.
SY: That was one of the key initiatives that Phil and I worked on. Before, we were part of each regional organization of Sony Computer Entertainment, so we were a little bit at arms’ length, and didn’t necessarily share information from an early stage. But after Worldwide Studios was formed, we have been sharing our technology and developing a common infrastructure. After two and a half years, the distance between the London Studio and Foster City in the US might as well be as close as the distance between London and Liverpool. I may be exaggerating, but we feel as if that is already happening."
http://threespeech.com/blog/2008/07/interview-with-sonys-president-of-worldwide-studios-shuhei-yoshida/
games will generally cost less as the generation progresses.
"Um, what? That money is split over several hundred full-time employees, as well as offices, equipment, expensive professional software, legal fees and other things. Also, they are paid for the entire length of development, which with some of these HD projects could be 7 years. So you have to factor in not 1 but 3-7 years of salary per person."
How many Sony games have been in development for 7 years if any ?
