Really depends on your flight dates. I did a quick scan of flights using Away.com's Compare Rates tool (http://away.com/plan-a-trip/compare-rates.html) and found r/t flights for between $1,100-$1,200 (with a stop in European hubs such as Amsterdam, London, or Paris). These were all flying out of IAD in mid-November. Bear in mind, this is quite last-minute, though flights aren't all that much cheaper if you were fly in February 2013, say. Fares will continue to increase as you get closer to the main spring/summer peak for transatlantic travel to Europe. Hope this helps!