GET was the nearly the entire shopping center. Inside was kinda of like a maze as what would seem to be individual shops were all joined together. As noted you had to join...prove that that you had a job related to government work (although there were a few scams to become a member). Members of the family would get a membership card. Prices were posted as what one might pay over in Stonestown, and then there was the GET price...generally twenty cents off on the dollar. It seemed like a good deal at the time. As I recall they carried decent products and provided customer service.
There was another version of GET called ALEC down by Daly City (or was it far enough south to be the start of Colma)? If still there it would be just east of 280.