Probably should just wait until the Aether's fate is decided. I know a few ideas have been kicked around for what to DO with the Aether... However, if the one idea comes true (of allowing anyone Aether access, but only Pilot+ can break blocks) then this forum might be a good way to get together for collaborative builds.
Is aether the end? If it is it might be worth paying for. I wouldn't want to spend $20k without knowing what I'm actually getting.
No, the aether is a sky lands generated world, not the end. It is a building paradise with and ABSOLUTE no greifing policy.