https://books.google.com/books?id=oaBOuo4mId8C&pg=PA189&dq=IBM+360++cost+billion&hl=sv&sa=X&ved=0ahUKEwiN2Ne5pt3OAhWsK5oKHZH_AMQQ6AEIWTAI#v=onepage&q=IBM%20360%

https://books.google.com/books?id=oaBOuo4mId8C&pg=PA189&dq=IBM+360++cost+billion&hl=sv&sa=X&ved=0ahUKEwiN2Ne5pt3OAhWsK5oKHZH_AMQQ6AEIWTAI#v=onepage&q=IBM%20360%20%20cost%20billion&f=false https://books.google.com/books?id=oaBOuo4mId8C&pg=PA189&dq=I... says: > Estimates of the total cost of System/360 range from $4 to $5 billion. Of this amount, $500 million to $1 billion was development cost, while the rest was used to expand manufacturing capacity and to produce rental machines. The references are Wise (1966b), Evans (1983 p.44), and IBM Annual Reports for 1965 and 1966. Wise (1966b) is a Fortune article titled "IBM's $5,000,000,000 gamble". I can't find the annual reports readily online. It looks like you want Appendix C of "IBM's 360 and Early 370 Systems" at https://books.google.com/books?id=MFGj_PT_clIC&pg=PA619&dq=IBM+360++cost+billion+revenue&hl=sv&sa=X&ved=0ahUKEwiiqsa4qt3OAhULBywKHSP9CYcQ6AEIITAB#v=onepage&q&f=false https://books.google.com/books?id=MFGj_PT_clIC&pg=PA619&dq=I... , with financial an employee data for IBM from 1950 to 1977. In the early 1960s IBM had revenue of over $1.5 billion/year. Even then, 360 was a big gamble.