I had a 7-day round trip in Iceland last July. My final total budget (excluding air flight) was $1,100 CAD per person (there were 3 people in our group).
What was included in our budget:
- Car rental;
- Hostel reservations;
- Food from supermarkets.
Total trip length was 2500 km.
Method of payment everywhere in Iceland - credit card only and everywhere. I did not change even a single dollar.
What did we get: a lot of fun, and this is the summary of what we could see in those 7 days: https://www.youtube.com/watch?v=w5bHYl7oT0I