Eric - the one Ken is talking about is the same block of the Waterfront restaurant. But Timo (of CL) said there is a self-serve one next to his mother's hotel in Sosua, but can't remember the name of her hotel. Ask him when you get down there.
Yeah, the one next to the supermerkado charged me 100 pesos to dry just 1 load. I had washed the load. When I brought it back to the house, they must have dropped one white pillowcase on the ground because it was all dirty like it had been drug in dirty pool of water. But instead of telling me, they folded it and put it at the bottom of the bag.