To the OP: Janice.dancer
Taxi from airport is around $20. Negotiate. Don't pay more.
Tell him to take you to either Metro or Caribe Tour.
Have you checked the schedule of either bus line to see what time their buses get to where you want to go>?
And, as on good poster has suggested Javilla is cheaper, and more "popular" than the other two lines...and yes, less comfortable.
It is an easy transfer. BTW, I don't think you have told us what time your plane gets in...a mighty important detail..
Have a good trip.
HB