I have a loncin 125 cc that I bought new for under $1000 US. It's been good for roughly 2000km. Still runs smooth and I've had no issues with it. It's a popular model in the Andres area and is easy to find someone to work on it. If you're a big guy you should go for higher displacement such as a 175cc.
Look around your area in Puerto Plata to determine which models are popular and easiest to find parts/mechanics. I wouldn't be surprised if electric models start hitting the market soon. I saw a few in dealerships Santo Domingo a year ago but the price point isn't quite there yet. They are optimal as they are super low maintenance.