For 500000 pesos you could well start a shop.
A kiosk (colmado) for example, selling liquor and things that people need daily.
The basic rules are probably the same all over the world. Especially important here is that you never ever may give something away in credit. The money is 100% lost here, no matter what.
You will need to have experience with latin american mantallity for that (people begging you to give you someting in credit, difficult customers, people trying to collect money and many other perils).
Also working: sell products to the thousands of colmados and small shops. You only will need a reliable car and some merchandise. A car for 200,000 and products for 40000 will do. Keep the rest in the bank for all cases.
With some of the products I can help you (affordable perfumes of high quality, Gilette razors, underwear and some other stuff).
Also what will work (but I do not do): Sell acrillic nails and accessories to the many small nail shops. The products you will get from chinese importers in Santo Domingo.
Of course it is not easy, but works as long as you do not start to give something away in credit.
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Investments in Dominican Banks: not recommended, and inflation works against you. If anything is sure here it is that promises are not kept.
If you invest in international growth stocks (not from the D.R.) you will probably get 15% over the years if you follow the rules of masters like Warrent Buffet. Not bad after 20 or 30 years. Buffet made 23% over his lifetime, if you make 15% it is realistic.
If you calculate 15% of 50000: 6250 pesos a month the first month.
If you are activly selling 25 days a month and sell for 10000 a day: 250000 a month. 1/3 your margin: 83333. Minus gasoline, repairs, accomodation: 2000 a day or 50000 a month. Difference 33333 . Reduce 1/3 to be on the safe side: You can make 20000 pesos the first month to be realistic. Of that money you have to put something in the bank to be on the safe side.
Just try it out with a rental car and products for 2000 pesos.
Importer