Cost was the 'decisive/deciding/determining factor' in their decision. [=the most important reason for their decision]
The 'deciding factor' was cost. [=the decision was based on cost; the least expensive option was chosen]
Costs increased/decreased by a 'factor' of 10. [=costs were 10 times higher/lower than they had been]
(..) in our current situation. - What the hell are you doing? - We must keep moving, doctor. Spock, this thing punched your iliac region. - Time is a critical factor. - That's exactly what I am trying to tell you. Look, I can't take this out. You are gonna die. Okay, if I take it out and can't stop (..)2016 Star Trek Beyond