Yeah, I hate that you can only buy this stuff when you are a member... I started a new charecter and Bastok is in 3rd so Numa (In "Galvin's Travel Gear") wont sell the lvl 8 MNK gear! I can't get any deals, I hate Bastok and the over priced AH!
I would like to point out that Silver Owl is not the only person that can dole out the Tenshodo Membership quest. Sutarara (a TaruTaru) can give it to you as well (2nd door on the right in Neptune's Spire). I believe you can also get it just by having built Tenshodo fame (in that Jabbar will give you the application without you having to first speak to Ghebi). Further information on how to efficiently complete the Tenshodo Membership quest can be obtained from that page (link provided above.