Return trips are a bit more expensive, but still very reasonable. For example, in September you could fly round trip from Newburgh, NY to Bergen, Norway for just $236:
Many other routes are also available. Remember that Norwegian is a low-cost carrier that charges for everything from selecting your seat to checked bags. However, those with a card like the Chase Sapphire Reserve or Chase Ritz-Carlton card could easily use their annual travel credits to cover those fees. Read more about additional fees and costs here.
A few highlights of the one-way pricing from the US to Europe include:
New York State
Newburgh to Dublin/Shannon from $116.80
New York JFK to Stockholm from $117.50
Providence and Boston
Providence to Belfast, UK from $84.40
Providence to Bergen, Norway from $84.80
Providecne to Cork, Ireland from from $116.80
Boston to Copenhagen from $117.50
Hartford to Edingburgh, Scotland $116.80
Oakland to Copenhagen / Stockholm: from $141.50
Oakland to London from $157.10
Los Angeles to Stockholm/Copenhagen/Oslo from $165.50
See full details of this sale on the Norwegian site.