I would HIGHLY recommend becoming a member of both ASIA and GAL if you can swing it financially.
I understand Kevin's point from a few days ago, that just because you join the association and get your certificate that doesn't mean you are a "luthier". Certainly that is true. I am one of those newer builders and consequently I tread very lightly with the use of "that word" and with the marketing of my guitars.
But I will tell you what I think the two biggest values of membership are:
1) The magazine. And not just the ones you get in the mail, the reams and reams and reams of information you get from the back issues. I have picked up some unbelievably cool ideas from guys like Kevin Ryan, Don MacRostie, Bob Taylor, Todd Taggart and a ton of other guys who are icons in the field simply by reading their articles. That information is invalueable to me.
2) The human association. Our forum is great -- I truly love it, but meeting ASIA members face to face at symposium was really fantastic as well. And let's face it, not everyone hangs out online like we do.
I made friends with several guys who are bonifide luthiers -- guys I might not have ever had contact with through purely electronic communication. Case and point, every time I call Bill Moll, even about ASIA stuff, I need to make sure I have a pencil and paper handy because I am going to pick up a new idea, new supplier, or something from our conversations.
This is certainly a TON more value than the $55 (or whatever it costs) annual membership dues. I absolutely think it is worth it to join the associations.