Oleg. In relaity price will be much higher. I would expect total of about $20-25 per couple (if you add flights to AU, to Cairns, to PNG and Barrier Reef with cruise).
About money, we live one life, so we need it in the way, (Ostorvski copyright) so we would't be sorry in the old age...

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Тост про женщин: Не так хорошо с Вами, как плохо без Вас