This receiver was used by the top government surveillance agencies worldwide during the 1990's (CIA, NSA, GCHQ, BND, etc.) Some countries may still be using it today.
Depending upon the installed options, it would have set the purchaser back from $25,000 to $40,000 USD.
ESM series receivers are highly prized by premium receiver collectors, radio museums, and amateur radio / TSCM enthusiasts. It is is considered to be one of the best communications receivers ever made.
More photos and a chance to own it, here.