You are in a pickle, the messiah! Or, are you a pickle? LOL The whole enterprise will get more confusing to you by the end of this thread, mark my words. There is some sort of a budget, some sort of availability (with you being down under), and this little pesky thingie some of us call "personal preference". Besides, you are (again, down under) in for a hot summer this year, I have heard with no spring at all (starts in about one month). Enough lecturing, right?
What you should do in your situation is to get her out, together with you, in a large mall where several lines are represented and start sniffing methodically. Contemporaries are good, classics are even better. Flirt with Sales Ladies, let them spray and dab on you both left and right, ask for samples, maintain the liveliest and loveliest of conversation with them -- they are people too! Let them fight for your attention and be jealous if someone else gets it. With all that you should arrive home with a handful of samples and please let YOUR LADY decide what she likes/wants.
And when Christmas is coming in the middle of the summer -- you will surprise her with the full bottle of her favorite.
Elementary, Watson (Women's Phsychology 101), non?