Via The Points Guy, you can fly from several US cities to Iceland in coach starting at just $200 round-trip!
I found flights from San Francisco to Reykjavik for $260 departing April 16, 2017, and returning April 27, 2017. These fares are valid for travel from April to June, and from September to November 2017 on certain routes.
Here are the details. And how to search for deals from your city!