Hey guys. I had a sneaking suspicion coming up to this patch that the 'Brawler's Pass', previously obtainable from different sources and notably is BoE and can be sold on the AH would grant access to the new one. And seems i was right. Brawler's Pass - Item - World of Warcraft
As of right now, if you have, or can buy one the "Brawler's Pass'" off the AH, you will be granted access to the NEW Brawler's Guild. This saves you having to grind out one of the new invites another way.