There is a little about G.E.S. on Wikipedia. It apparently operated in several cities in both Canada and the USA (mainly along the east coast, but having a concentration in the Washington D.C. area), and even a few in England. It was also called G.E.M and G.E.X. (Government Employee Mart and Government Employee Exchange). I remember one of those stores in the D.C. area from back in the late 1960s. There was a requirement that members be in some way employed by a federal, state, or local governmental entity. There is not much detail provided in the Wiki article other than it operated from about 1959 until 1973. At some later time, it eventually became Circuit City (which is now also history). I never much liked Circuit City.
Back in that same time period, there were many general merchandise discount store chains which started up all over the country as the result of the weakening or elimination of the "Fair Trade" laws (basically intended to fix high retail prices for all sellers) then existing in many states. Most of the chains didn't survive beyond the 1970s due to the intense competitive pressures.
