I am not sure about internet CAFEs, there are definately LOTS of internet centers in la capital and in all around DR, but I wouldnt know about the cheapest rates...for using the internet? its not THAT expensive. The only place that had a cafe like setup was in Santiago inside the mall, on the 2nd floor there is a cute, modern looking cafe with i believe a coffee/ice cream shop as well.
Like Rio said too, lots of places have free WiFi just need to know the spots. hotels in the north coast are starting to give this free to their guests so thats always good if you have a laptop!
