How's your Spanish and will u have a ton of luggage? For me, who only carrys a back pack, I would either walk or guagua to the autopista Las Americas (walking in daylight only). There is a pretty major parada (bus stop) there. I'm guessing the guagua is only 150 pesos but I don't know. Then, take the San Pedro guagua all the rest of the way.
But if this is your first time or you have a lot of luggage or your Spanish sucks worse than mine, then I would do Uber. I have never done it but can't imagine it's over 2000 pesos.