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]
(..) its the wrong time its a terrible idea, you got the economy, you got the credit bubble, the supreme court look at Haiti i guess i didnt think about that well you know, its a factor who are you? -Flash Gordon, quarterback, New York Jets this is the american fantasy right here (..)2012 Ted