Norway in a nutshell vs simple train trip

Norway in a Nutshell is way more expensive than the simple point to point train ride- Bergen to Oslo you can get for under £40 (US$50) or about £80 to £100 even booked on the day. £40 for a train trip of that length in an expensive country is something of a bargain.

But you miss the fjords trip and the Flam Railway (but get the Myrdal to Voss section through the mountains which everyone misses).

It's the premium pricing on the Flam railway especially which pushes the price of Norway in a Nutshell up, and to a slightly lesser extent the boat trip through the fjord.

A good half way house between a straight train ride, and Norway in a Nutshell is to take the Bergen to Stavanger bus down the coast (the bus drives on and off two ferries en route) and then the Stavanger to Oslo train. Some of the bus departures now have double deck buses on them. It is one of those under rated trips in Norway, being just normal public transportation, as it's primary function.

The Oslo-Bergen train trip is lovely and an attraction in and of it itself.

Norway in a Nutshell is a combination of train/boat/bus legs that show multiple
features of Norway in a compact package. It is a separate attraction and worth
considering, whether you arrange it yourself or buy a package deal from an agency.

You can do NiN on the way to/from Bergen, but it may be easier to do it as a day
trip from Bergen, as this avoids managing your luggage, or, spend a night along
the way in Voss or Flam.