Hard NOT To Find
There are quite a few ballezas, one on Duarte near the middle supermercado and one in the newer "mall" with the cambio on the Duarte end and the Pharmacy in the tunnel that goes to the alleyway paralel to Duarte.
Plus approximately 100 manicure and pedicure offers on the beach (including ones where they only deal with "one" appendage) , you should have ample supply.