Go to a large store like Plaza Lama ( several locations in Santo Domingo ) and you can get a new phone with accessories for between $ 2500.00 to $ 7000.00 pesos (and up, depending on model,etc.) For example, I recently bought a Motorola Star Tac 3000 with hands free, home charger, car charger, clip, leather case and battery for $ 2700.00 pesos RD. I would not risk buying a used one from an individual ( and believe me, people will push hard!!!) as the difference in cost is small compared to the possiblity that it has a problem that you will not discover until you go to have it programmed.
Good luck!