I took the bus from Bergen to Oslo, because I was going to visit an expat friend who had a cabin along the way.
The bus was very comfortable and sometimes stopped in what looked like the middle of nowhere to let hikers on and off.
We had one rest stop at a cafeteria/souvenir shop where none of the wait staff spoke English (unusual for Norway), but with my pidgin Norwegian, I was able to get a meal.
My only regret is that we were not able to stop at the three stav churches (wooden medieval churches built with Old Norse architecture) along the way.
Total cost: about US$100.