Reader Elliott just alerted me about the WOW air sale for the Boston route and the new BWI (Baltimore, Washington D.C.) route to Reykjavik for $99 one-way.
There aren't a ton of seats of left, but especially from Boston (not the return though) I was able to find a number of dates with the $99 all-in one-way price. The return can be had for as little as $172. At $271 for the return trip, this is still a smoking hot deal (to a cool location).
While Boston has daily flights pretty much from March, the flights from BWI start in May and are more restricted.
Reykjavik is a fantastic destination – the city is a great urban space (much more than you'd expect from a small, remote country such as Iceland). The Blue Lagoon is a must-do and one of my favorite travel memories. Here are more To Dos for your trip.
Please share any dates you have found in the comments to help others (feel free to book first).