Iceland is pretty damn expensive, probably one of the most expensive nature destination you can find, together with Norway (although Switzerland probably still wins the prize).
I went there in the winter (when things are generally a bit cheaper) a couple of years ago and it wasn't too bad. Food, however, was incredibly expensive everywhere. No where else have I spent nearly $20 USD for a meal at a fast food restaurant.
I went to a number of local places and they were all about the same as this. I even went to a fish and chips place in Reykjavik expecting it to be cheaper since they certainly don't need to import fish, but it wasn't. Another tiny family-owned restaurant in Vik was the same as well. I honestly couldn't find cheaper food.
I do understand the difficulty in importing food to an isolated island with only 100k people. I'm just not sure that fully accounts for the increasingly high food prices across the board.
yeah, I've seen a lot of people saying food in Iceland is super expensive, but when I was there it was about as expensive as any American city. I think many tourists must still be going to like Subway. I was going to the local restaurants and even found an amazing noodle soup place for under $10 equivalent.
Every other person I know that goes to Iceland subsists off of hot dogs. For dining out at restaurants in Reykjavik, the cost has been comparable to tipping well at middle to mid-upper US metro establishments that aren’t chain restaurants ($20-$25 / entree as of 2014 when I went).
Food there has gotten really expensive the last few years. Getting there can be really cheap though. I've now spent two Thanksgivings there where we paid less than $1k/person for flights from US west coast and a very good hotel for 3 nights.