For these kind of deals to stack up you need to purchase the whole block and obtain insurance quotes from a good broker in advance.
In fairness to Nathan cyclone Yasi struck in 2011 from memory and insurance premiums only really spiked for units to ridiculous levels in the following few years. Unit prices were smashed in Cairns a result and have not really recovered compared to houses IMO.
The market has since priced units in Cairns accordingly.
Not having a go at Nathan, it is purely my thoughts about why I do not like regional towns. As the risk is so much greater but so can the rewards to.