Worth remembering that excess funds can only be returned to owners (in NSW) if there is a unanimous vote (as in, no votes against) to do so.
That could be a bit of a problem. What I was thinking of was more along the line of with a 50 lot building was to have $20k as a buffer. Having seen plumbing jobs take $10k because of difficulties finding the leak and then diverting the flow and then patching up the places where they gained access, it is better than suddenly needing a special levy.