My trip to Iceland was at the end of 11 months travel and I only had 3 weeks left overseas. I was in Europe and wanted to go somewhere new, but I had a limited budget with very limited funds at the end of my trip. Using the Skyscanner Search Everywhere feature, I found a flight from Warsaw to Reykjavik for only €20! There are lots of Polish living and working in Iceland, so flights from Poland are often relatively cheap. Naturally, I booked it immediately, and figured out my plans going forward. I was determined to do this trip and see the northern lights for the first time. For help using the Search Everywhere feature, check out my page on Finding Cheap Flights.
The main part of the trip was a 7-day loop around the M1, visiting the main tourist sites, several added bonuses, and more hot springs than I can count. I also did 3 days in Reykjavik, for which I couchsurfed and hitchhiked around Reykjavik, including a full day at the Blue Lagoon (I was the first to arrive and last to leave - gotta make the most of your dollars!).
I visited Iceland in November, and can confirm that hitchhiking in winter is very difficult, generally unsafe, and not recommended. I spent three days hitchhiking around Reykjavik and it was very difficult to get a ride as it's dark, wet, people can't see you well, and it's too unsafe for cars to stop suddenly to pick you up. When it's raining, it's also a lot harder to get rides as people don't want their cars getting wet. Plus waiting on the side of the road for a few hours is not an ideal way to spend your limited daylight hours in the winter. Lastly, if you were trying to hitchhike the road on the M1 and you needed to get out of a car for safety, or for whatever reason your hitchhiking driver left you somewhere unfavourable, you could get stuck somewhere remote, very cold, and with minimal traffic. There is a genuine risk of freezing to death if you're on the road in the middle of the night and no one can see you. It's just not worth it.
In the summer however, I've been told by many people that it is a lot easier to hitchhike and that people are happy to pick up travellers. I haven't done this personally (yet) though, but the official GuidetoIceland.is page has a great Hitchhikers Guide to Iceland that you can read through!
Lots of people travel around Iceland in a car, so I used Facebook to connect with other travellers to share a vehicle and the trip. I was surprised that I got quite a few people who messaged back - even in November - although eventually I met two amazing Canadian men who had the same travel dates and budget objectives as I.
To find potential travel buddies, search "Iceland Travel" in Facebook, and join whichever group seems to be the most active - in the below screenshot you can see two pages that have 10+ posts a day. Join the group and ask if there's anyone travelling around on the same days as you. I had 2 nights before and one night after my Canadian friends left, but otherwise the dates worked perfectly. You may need to scroll and read a bit to find someone whose trip matches yours.
We paid AUD$455 for our Jeep Jimny, although we were given a free upgrade to a larger Jeep by the hire car company. For information and help on finding cheap hire cars, check out the Finding Cheap Hire Cars page - this page actually uses the example of finding prices for hire cars in Iceland.
Below is the list of the fuel and groceries that we paid for. We did around 1,700km - the ring road (M1) is 1,321kms, and we did many detours, dipped into the Fjords, and ran the car at night for 20 minutes to warm us up if it was especially cold.
I didn't keep an extensive list of groceries, but we had no cooking gear with us, so the below are the total costs of our food. On one of our grocery shops we purchased hotdogs and boiled in Grjótagjá Cave for dinner that night. This hotspring cave was hot enough to boil our dinner in, and I've never had more delicious hot dogs!
We only had to pay for parking once, and this was before the guys went on the Vatnajökull Glacier Hike (which was a separate AUD/CAD$250 each).
There are a few things that weren't in our communal budget. One person didn't do the glacier hike, so the other two paid for theirs separately. We also went to the Bjarnarhöfn Shark Museum where two of us tried Hakarl - fermented shark - which cost 1800 ISK (AU$21) per person. Lastly, on the final night we ate out at a restaurant and two of us had Svið - sheeps head - for dinner. This was the most expensive thing we purchased, costing AU$35 / ISK3000 each.
It is definitely easy to spend more in Iceland - but here's the bare basics and unavoidable costs we accrued in our trip: