Last time I priced them the shipping containers could be purchased between $3000-4000 from companies that buy them up and resell them. Getting a loaded container to port is the next costly challenge. If you were going to do this often you should get a contract to negotiate a 1-2 times a year shipment for the transport of items by truck. Negotiate a say 2-3 container minimum a year with option to add to that number at a reduced cost rather than the typical one time affair. You would have to ball park your weights for estimates but you will always pay actual weights of pay for a minimum weight.
You would need to ideally crate them for best handling when in country with fewer issues with damage. There are some great crate systems by some of the more expensive motorcycle movers which would be the way to go & imitate their ideas. If you used Corroplast walls you could arrange to sell it to RC folk or to a sign shop. It won't have the strength of a plywood but it would be lighter and provide decent protection unless something heavy fell against it and sometimes thin plywood would not be enough for some blows. Plywood would be better in those negative instances. Unless you rented a container, it would be better to do one way trips with containers unless you were to find Australian products that could be imported, or other country's products that could be packed in your MC crates and the container load return. If you rented a container they could pick it up after unloading but that requires you to have space to store the load safely.
There is a huge glut of containers at ports from all the stuff being imported and the containers are used as a one way use.
You would be able to fill your container as many Australian guys want stuff from US or even a bike from US and cannot afford the hit of shipping. So, if you were a bonded agent, then you could accept orders of things for them. You would have to inspect any packages to confirm the shipment was complete and accurate. If you
shipped smaller containers, rather than the typical full sized, then it would work out better. Doing t this would work better for Australians wishing to use you as a intermediary or agent/broker/proxy. Shipping more often would reduce your capital outlay as well. To piggy back this service you put a removeable shelf system that would safely load items above the palleted bikes.
In country you would need a truck for transport , commercial truck...or rent a truck and trailer, or buy one
Just some thought I have on embarking on such a business adventure.