I'm not sure that ISBN's are
that international, so to be on the safe side I'd take the full title of the book with you too : The "Times" Su Doku: The Utterly Addictive Number-placing Puzzle: Bk. 1
Which is what it's called here. Sometimes they change the title of a book for the American market (or vice versa for the British).
As for availability in Australia? No idea how you'd find out about that, except for asking the bookstores where you live.
PS this website http://www.nikoli.co.jp/en/
ships to both Australia and US. Interestingly it also states that Gekikara is a Super Hard Sudoku, for those who find the Very Hard in the Program too easy