If I am not mistaken a Clan level 2 can already auction for a Clan Hall. If that is a wrong info (for which I apologize), then I am 100% sure that a Clan level 3 can auction for it. Level 4 needs a quest and everyone can have a Clan Hall before questing begins. So level 3 is definitely giving you a chance to auction for your Clan Hall.
If you have a chance and can spare that 20.000.000 adena + 10.000.000 adena per week, be sure to grab yourself that Clan Hall as soon as possible. Trust me, you won’t regret it!