cruise travel

possible trip on the Diamond Princess ship, visiting Xiamen docking 7am sailing 2pm on the 11th September 2015 and Hong Kong docking at 9am sailing at 6pm. this means with disembarkation time and embarkation time that has to be allowed we would have 3 hours in XM and Hong Kong about 7 hours. Would we qualify for a 72 hour transit visa? If not what visa would be required? and the cost. we are Australian born citizens. there seems to be several groups offering visas for varying amounts.