To upgrade to CAT II or III ILS will cost a lot of money. We'll pay for it throughout the year in ticket pricing.
I dunno....I don't think that's necessarily the case. Though who will ever know

Melbourne Airport/VIC Government/Airlines/whoever else is involved have obviously considered CATIII a worthy investment. Somebody has done the calculations and it's assumingly due to increase tourism and business revenue for Victoria with the intl termninal expansion, that the upgrade pays for itself.