You can actually just go to the Glock authorized dealer and sign up. Pay $35, and they will let you out the door with your membership sent off to GSSF. It is usually $100 cheaper so you save $65 with membership. My dept pays our GSSF membership for the armorer coarse. The local gun shop sells them to us for $200 off, so we utilize the GSSF + $100 and the single magazine they are supposed to keep out of the box. So a total of 3.
I was not aware they offered them to civilians but talked to a guy I work with that works at the gun store. He said they do for 1 or 2 months each year. And they are the same price as listed to LEO. I don't know personally, but he is very reliable so I always trust his word.
Good Luck