Delta Airlines has New York JFK to Dublin at $523 to $533 for departures from mid-November to February 2017. American Airlines has a much longer season from Philadelphia with Dublin tickets at $553 from October to June 15, 2017. Delta tickets are priced around $555 for travel in October and March to June 15.
$532.52 round trip (Air France codeshare ticket for Delta flights) Sat Feb 4 – Sun Feb 12
Aer Lingus New York JFK – Dublin DUB nonstop
American Airlines Philadelphia PHL – Dublin DUB nonstop
While these are reasonable fares to Dublin, there have been deals in recent months with ticket prices dropping to upper $200s/low $300s round trip. This is a decent deal for planning a trip Oct-Dec, but I’d hold out for a lower fare opportunity if planning to travel in 2017.