Again, I spoke with Apollo Taxi. I use them every day here in Santo Domingo. They work on a tariff bases. They WILL pick you up ANYWHERE in Santiago. When you call for the pick up, ask for tariff again as it can change slightly based on gas prices and the exchange rate. Also ask for the unit number (unidad) of the taxi they are sending. The car will have a plate on the windshield that clearly says Apollo and the unit number. If the driver asks for a cent more than you were quoted on the phone, tell him to get on the radio and request the 'Tarifa'. Also, if you want A/C, tell the dispatcher. I just called them again; the rate with A/C is $2900 pesos. The dispatcher I just spoke with said for that type of fare/distance they will always send a newer vehicle. I have never had a problem with Apollo or their drivers. If you have the money, you will reduce your travel time from 3.5 hours minimum considering getting to and waiting for the bus, to about 1.8 hours door to door. I remember the trip on Metro that I took one time from Santiago to SD. I remember entering the city of Santo Domingo and thinking great, we're here! WRONG. That giant bus takes an hour just to maneuver around SD to get to the terminal. Plus, the taxi is yours, no foreign odors that you may not enjoy. Also, the taxi will stop if you need to use the rest room or need to buy something to eat or drink. I ALWAYS make the guy stop right near Bonao to buy Cerdo Asado (Roasted Pork) that they sell right on the side of the highway. If you like to coat your arteries like I do, you'll love it.
Which ever you choose, I hope you have a pleasant trip. Please feel free to send me a PM if I can be of any assistance.
Also, I always tip the driver if he's cool. 100 pesos is a fair tip for the ride you're taking. It is not mandatory, nor is it customary here, as the other board members have pointed out to me on many occasions. I do it because it makes me feel good!
If anyone knows a taxi company IN Santiago, perhaps you could find this guy a tarifa there. If he is flying in it will be very inconvenient for him to wait for a taxi coming from SD.