tintiNZ:
Abebooks would be your best bet.
I always hate to set values on such things, but you could get four figures (Aus $) for it, so keep that in mind when choosing how to sell it - getting it in front of the people who want to buy it is key!
I think you have to be a bookshop or dealer to sell through ABEBooks, don't you? Could be wrong.
You could choose to hold an auction on eBay or through Catawiki - the later has regular Tintin and Hergé sales, which it promotes, which could help, where eBay seems to be a little more passive.
I don't think your being in Australia is a problem, to be honest, as there will be people all over the globe looking to buy this, and the postage, insurance etc. would be paid by them.
The cover is a little bit damaged, which might detract, but the inside looks clean and unfaded, and the pages are remarkably unbrowned, which is a real plus.
Good luck, whatever you choose to do with it!