They both had effects. I personally know people who quit smoking when it got expensive (for different levels of expensive). I also personally know people who quit smoking when they were convinced that it was unhealthy.

Though all of the above quit before 1990 (US). Anyone who still smokes today, knows it is bad and costs money: they don't care.

Now that I think about it most who quit because it was expensive were probably influenced by the unhealthy part, but it was the cost that finally tipped them over.