Air China is offering return flights from Melbourne to Okinawa, Japan for $673 and Sydney for $687. Flights are late October & November. Flights include bags and meals.
Layover/Stopover: Flights have a short layover (~2 hours) on the way there but a 8 hour layover in Beijing on the way back. This would be enough time to check out Beijing for a few hours on your stopover. China offers a free 72 hour transit visa so may as well make the most of it. Alternatively, you can add a 1 day (or longer) stopover for $10 if 8 hours is not enough. Skyscanner: Multi-City 1 Day Stopover. So for example, fly in Wednesday into Beijing from Okinawa, fly out Friday 1AM back to Australia. You can connect via Beijing & Auckland on the way back but I've been unable to get a free connection in Auckland, but worth having a play if you are interested.
For a further adventure, Jetstar Japan offers cheap return flights (~$160) to Tokyo from Okanawa in October so you could possibly work that into your trip as well if you can match up the dates.
There has never been an Okinawa deal posted on Ozbargain but flights from Melbourne and Sydney usually range over $1000+. Supposedly, Okinawa is known as the Japanese Hawaii given it's nice beaches and it's very southern position which provides a mild climate for most of the year. October will be 23°c-27°c on average. Non-beach wise, Okinawa is historically significant in that it hosted one of the biggest battles in WWII.
I went to Okinawa last week, beautiful part of the world
You'll fly into Naha, you need to rent a car if you want to explore the mainland, there is some nice beaches, huge caves, aquarium with whale sharks, historical sites, pottery, good food on the main island. You can get top to bottom in about 1hr 30mins to 2hrs.
From Naha you can take a ferry across to the closest island of Tokashiki, we spent the day snorkeling at Aharen beach (everything available at the beach to hire). This was the highlight of the trip, beautiful white sand beaches, super clear coral filled water, clean and everyone having fun. Would love to go back and island hop!
PM me if you have questions or want some tips :)