I just returned from Santo Domingo and stayed at a place called "Maison Gautreaux." Let me tell you, I thought it was wonderful. We paid $47 US per night which included taxes. Both me and my girlfriend stayed in the room so the cost per person was cut in half.
The hotel is near the Malecon, great location. It is possible to walk to El Conde, or down the the stip of hotels such as the Jaragua, Melia and the next one. (can't remember the name...sorry) Lots of places to eat around there, great security at the hotel, rooms clean, service was wonderful. There is no restaurant in the hotel / guesthouse, but as I said, lots of places to walk to very close by. The hotel does have beer and water available at the front desk. It is definately a place to try if you are on a budget.
They have a website if you are interested...
www.maisongautreaux.net
Would be happy to answer questions if you have any regarding this place.