The Dominican currency is the Dominican Peso DOP. As of June 2012, the exchange rate was 39.03 DOP/$1 USD.
One of the best spots in the Colonial District of Santo Domingo to shop is the several blocks long outdoor mall, El Conde Street. It offers everything from street vendors it is not recommended to eat off these to knock-off name brand clothing for extremely inexpensive prices. There are some very pleasant outdoor restaurants that serve as perfect spots to people watch and drink Presidente their most popular beer.
During the day, there are also several touristy shops where you can buy cheap presents for the family back home including authentic paintings and beautiful jewelry. There is also a very nice cigar shop at the end of the mall across from the cathedral. Clothes, however, are generally very economical and often of good quality. Most prices can be negotiated. US dollars are accepted in most areas.