So a swiss newspaper did some article about the development of GoW A and i found this part to be interesting:
Rough translation:
"how much the developnet of a game costs is usually not disclosed. However lead producer of God of War Ascention Whitney Wade said that they invested a medium sized doubble digit amount of millions. Meaning the development of the newest GoW game cost about 50 million dollar.
Keep in mind that UC and Havey rain apparently only cost about 20 mil dollars.