Self-catering in Scandinavia [closed]

I'm planning a driving trip from Copenhagen to Norway. I understand that Scandinavia is expensive. If I want to rely on self-catering as much as possible, how much should I budget daily for food for two adults? (I suppose a sub-question is, how much will costs vary as I cross from Denmark to Sweden to Norway?)

Edit:

We're talking about fairly simple stuff like bread, cheese, produce, and coffee.