Campsites in Norway are reasonably priced, much the same as here, but remember 'wild' camping is allowed as well. We found some really nice places to make overnight camp which cost us nothing, and the facilities at garages are much better than here, some have showers as well as toilet facilities. The food is much the same as here in the shops too, but it's very expensive to eat out. There are regulated shops for buying alcohol which is very expensive, so as suggested previously it's best to take your own with you.
We were fortunate as we had friends in Bergen and Oslo to show us around and they were great hosts. The Norwegian people are fantastic, their humour is great
My advice is give it a go, you won't regret it, but make sure you take some warm clothes with you