You can find an agent anywhere in Sosua. A simple stroll down Pedro Clisante avenue will expose you to a large amount of advertsing by all sorts of agent. One method is giving lots of different agents a "trial run." That is, try out a few and see what your gut reaction is. If they give you some sort of creepy feeling while they are showing you properties, then call it off. You can find local Sosua agents here.