In Iceland eating out costs a bit more than in the rest of Europe but, exactly as I said for Norway, you don’t have to be so worried and bring stocks of food from your country! Just not be fussy and if a a place does not inspire you because it is not for tourists that’s probably the best place to eat, if breakfast is abundant in your hotel no one will tell you anything if you carry off a sandwich, in the roadside the sandwiches are not expensive and if you are outside the tourist spots with 7 euro you can quietly eat a sandwich and drink.