I think that having the option to have a dedicated crafter in your guild would eliminate many of the concerns the devs have with high level items flooding the AH.
You could make items for guild members that are bound to guild, and sell an 'item depository' for the airship so that members could contribute to their crafters progress. If a user quits the guild, the items get removed from their inventory and back to the airship.
This is just a rough idea I threw together, but feel free to flesh it out.