I haven't trade with them. If you are looking for Australasia I can recommend Tom Osbourne who is in New South Wales. I've traded with him periodically for about 10-11 years and he is the consummate professional- easy going, flexible, kind, knowledgeable, and reasonable. His website is humorously old and locked in a late-1990's time capsule, but he issues gorgeous PDF price lists that are updated constantly. His stock is varied and extremely deep for Australia, AAT, PNG, Xmas, Cocos, Norfolk, Nauru, Pitcairn, etc.
His website:
http://www.stampdealeroz.com/His price lists:
http://www.stampdealeroz.com/pricelist.pdf