Are there any cheap ways to fly to Europe from the East Coast of US?

$900 is a very cheap fare for the high season. If you can wait until November, there are flights from Dulles in the $730 to $770 range to Bilbao, Madrid or Barcelona. However, you have to fly Turkish Airlines and change planes in Istanbul to get that fare.

US Airways does have some options from Washington to Madrid for $849 in August; most of them fly in and/or out of Regan National airport rather than Dulles. However this fare is only available on certain dates.

Kayak Explore is a good site for finding flights from a specific airport to multiple places in the world and allows you to select a specific month or season to search. http://www.kayak.com/explore/WAS/ When you find a price do check the airline website to see if it's cheaper there.

I'm going to the same place, and my trip is multiplicity and cost $1268. I bought it in May 2014. So you need to grab this one.

900$ is a miraculously low price for this time of year. If you want cheaper, go in January.