This $250 round trip fare from Boston to Iceland caught my eye today for flights for October to December 2016. There are dates in September at $290 round trip if you want less chilly weather. There are numerous departure dates at $100 one-way for BOS-KEF, even in September. The low fare for KEF-BOS is $189 beginning in October and $40 more in September.
WOW Airlines Boston to Reykjavik, Iceland KEF
$249.98 round trip Saturday October 22 – Wednesday October 27
Plan on $39 each way for one carry-on bag or $49 for one checked bag in each direction.
Still, hard to beat a $328 fare at $290 round trip and $78 carry-on bag fees.