The biggest and best place in Santo Domingo is Omega Tech, actually they are the biggest in the DR. They are the ONLY place I would recommend in Santo Domingo.
The warehouse is as big as most large supermarkets in this country.
They are located on John F Kennedy, 50 meters east of Nunez de Casares, just past the gas station, I think it's an ESSO. You can't miss it, large building with parking out the front.
The owner's name is Alvin, ask one of the sales people for him. He's a super nice guy and speaks fluent English. Tell him Robert from DR1 sent you, he will look after you.