Flights to Europe are really expensive this year! The EU government seems to be taxing the tickets heavily. You will unlikely find anything under $700 with all taxes included (even if the ticket itself will only be about $3-400 of that). Try to go away from a holiday travel day and you should get that deal.
Travel closer to Xmas or Carnival and you’ll likely pay closer to $1000 for each ticket. I know that IcelandAir and AerLingus are offering specials, but you’ll have the whole layover to deal with which may not be worth the $50 or so you’d save.
Watch these videos to learn how I find tickets for under $600 (almost) every time.