There are three major plane companies within Norway. SAS and Widerøe has mostly fixed prices, and you can get quite cheap youth fare tickets if you are under the age of 25 even if you book the same day. Remember to click on "youth fare" while searching for tickets. Tickets booked with SAS include luggage of 23 kg without any additional fees. Norwegian has often the cheapest offer if you plan your trip in advance, but remember that they have additional fees for luggage etc. Check if your flight is on time at Avinor's webpage.
Theres only one big railway company in Norway - NSB. If you book your ticket early you can get "minipris" for only 199 NOK - independent of how long you travel! They also offer student prices, remember to bring your student ID!
All Norwegian bus companies offer student prices (remember your student ID), and its often cheaper to buy a return ticket. Lavprisekspressen in direcion Oslo to Stavanger, Trondheim and Kristiansand and provide you with free internet and free coffee/tea during the trip. Nor-way cover the most parts of Norway, and have "place guarantee" which means that if the bus is full and you didnt book a ticket in advance, they pick you up with another bus!
There are many ferries in Norway. When you take the bus, the ferry is included in your ticket. If you walk its not so expensive. If you go by car, the driver is included in the price, but you have to pay extra for each passenger.
Hurtigruten is a cruise ship that takes you all the way from Bergen to Kirkenes through beautiful landscapes and fjords. It stops many places on the way, but keep in mind that this cruise is very expensive.