A great casa de cambio is El Efectivo in Plaza Metropolitana, which is at the N.W. corner of Ave J.F.Kennedy and Ortega y Gasset. Telephone: 683-9344. 5 minutes away from Plaza Naco driving, or a 10 minute walk.
You enter the central parking for the plaza from the westbound lanes of JFK. Park there. Go to the stairs on the eastern side, located under the pedestrian bridge over the center of the parking. Go up one floor, turn right at the head of the stairs, and go to the first door. All of the windows have dark tint, but once inside you are in front of the cashier window. They have consistently given me the best rates in Santo Domingo for the past 10 years.
If you don't want to go that far, there is always the guy in the wheelchair in front of Plaza Naco. He's normally out front somewhere between the ferreteria and the central entrance to the 2nd floor. I think he's honest, because he's been in the same spot for at least 10 years - just be careful of your surroundings and don't change a big wad.
