You don't need someone with a website, blah, blah, blah...Here's what you do you go around town in Barahona and find several houses that look well built, then you ask the owners to get you the info of the maestro who built it. Get a Dominican to call these maestros and give you quotes for the entire project, minus building materials (That you should buy yourself). Once you have agreed on price and milestones (partidas) you then make sure that you're there every step of the way during construction.
Make sure that things like water cold and hot work nicely and with good pressure BEFORE walls are finished, that every drain has the proper slant to drain ALL of the water, that electrical outlets are spaced out and at the height you want, etc, etc...
Have a Dominican negotiate discounts for you with the local hardware store, since you're going to be buying in large volumes.
Get your own plumber, electrician, wood worker, etc...don't necessarily go with the recommendation of the maestro or if you do make sure you see their work beforehand.
Prepare yourself mentally for some frustrating times...