Mcedic,
Welcome to DR1, your friendly everything you ever wanted to know about the DR message board.
Your trip from PC to SD is cheapest if done by bus. Having said that then be aware that the trip will take about 3 hours to complete so you are talking about 6 hours travel time to and from and depending on what you plan to do in SD will dictate as to how much time you will have to accomplish your mission.
As Riravaga said be careful as to how much jewelry and such that you may wear as things like that plus cell phones have a tendency to cause a person to maybe try to take it from you. This is especially true as we get closer to Christmas. Those normal precautions that you would use in your own country.
Enjoy your trip with us here in our little part of paradise and if you get a chance how about writing up a trip report for us when you get back home. We would enjoy to hear how your trip went. We have a "Trip Report" forum for such reports.
Rick