Bus travel from Salgótarján to Nagymaros on Easter Sunday
score:0
Accepted answer
As it turns out:
local tourist information office didn't provide correct info (they told me that I need to travel via Budapest, but I was able to make it via Balassagyarmat just fine (which was my original plan)
timetable search at http://menetrendek.hu works fine, but it's not available in English, afaik. After some clicking around, it's usable, though. And it has a mobile version, too.