In the last couple of months I have had fish shipped to me twice, once from Auckland and once from Hamilton, both times fish arrived in perfect condition, only lost one but that wasn't the couriers fault. Cost me $35 both times incl. box, heatpads etc. That was through posthaste and both were here within 24 hours of them being dropped off. As long as they are bagged and packed properly you should be fine even in these temperatures, what sort of fish are you looking at getting shipped? Mine were dwarf cichlids and small plecos.