One-ways aren't always that hard to find. I constructed my trip in December/January using only one-ways. Matter of fact, I can fly from Dublin to NY (EWR) for around $200 all-in on March 9...March 29th...March 14th...etc (three random dates I chose)
Raysen...if you'd like, I can assist you in finding cheap flights.
However, I need specific information. PM me if you'd like help.