From Melnik to sofia by bus: leaving at the busstation at the park, duration is about four hours and it costs 7 lv. From Sofia to Melnik, a bus leaves at the Princess Hotel and leaves at 6 am. From Sandanski busses leave at the Hristo Smirneski street and leave at 3.30m and 5.30 pm. From Melnik to Sandanski they leave at 4.30 and 6.30 pm.
Melnik is approachable by car and buses. We rented a car in Sofia and drove to Petrich and from Petrich to Melnik. Roads are narrow and dogleg very often, so be careful as a big tourist bus might show up sudenly from nowhere (esp. once u leave Melnik in direction Rojen monastery)
To travel to Melnik you have to take the road that is going south from Sofia dierection Kulata or Thesaloniki, Greece. Then you travel south till you reach almost Kulata. Some kilometers before it there is an intersection that brings you directly to Melnik. It is actualy the last town on this street appr.10 km away from the main road.