This is an outstanding deal as flights to Isarel are very expensive and rare to see under $1,000.
To book you need to use a European travel website called Wideroe. They are most likely not calculating taxes or fuel surcharges properly since these fares are not available elsewhere. They had a similar mistake in January I believe for flights to Italy that were pricing at $284 round trip!
Availability is best through June 2014 but keep looking and cheaper dates are scattered the rest of the year.