http://covoiturage-lasterrenas.com
People share Taxi ride now from SDQ, but it is harder for us living in North America, since it is usually at the times of Euro flights such as Air France or Iberia, but you never know.
If you need a taxi, I have a couple reliable ones from LT, nice van, wifi, been using him for 5+ years. PM me if you need. The price is $180.
Transporte LT:
SD - Las Terrenas :
8:30 AM - 9:30 AM- 11:00 AM - 1:40 PM -3:00PM - 6:00 PM*
*Add 30 min for the parada Samana. Really easy, close to the airport. 375 RD pesos.