I hope you are well, not long now to your two weeks off, I assume you are looking forward to.
The watch you have asked for is only available in Thailand and not Australia. It appears that a different market exists there, which is why Seiko and Casio release different watches in your country.
I have a Casio G-Shock Watch and I have one for my son. His I bought from England and then mine I bought in MBK in Bangkok which are exactly the same. A lot of things like this are expensive in Australia.