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]
(..) they might just save your life. Set your watch for ninety minutes. - Why ninety? Well, Houston clocked that debris at fifty thousand miles an hour. If you factor in our current orbit, then I figure we got about ninety minutes before we get our asses kicked again. O down to six percent. - Okay. (..)2013 Gravity