Hi there Doc Jason!
Well, it seems Buzzcut was refering to me.... I do live in Makati.
I've been a member of basenotes for quite sometime now and have contributed a number of posts.
Before anything else, I would like to welcome you to Basenotes, the premiere web resource for fragrance enthusiasts from all over the world. Basenotes have been a great help to me in my decisions with regards to my "little" fragrance hobby. And I hope you will enjoy your stay here and that Basenotes will be of help to you in your quest for the best scents out there.
With regards to your question, Roberto was right in mentioning Rustan's as a good place to shop. They do have a wide array of fragrance selections that you won't find in SM Malls and other department stores. And yes, they have the typical designers scents and they also carry some niche scents like Diptyque, L'Occitane, L'Artisan, Keiko Mecheri, Annick Goutal and a few others that i can't remember. If you are the type of person with deep pockets then you can find some scent there that is to your liking. If i remember it right, the niche scents there would cost you around 5,000 to 6,000 Pesos (US$100) for a 100ml bottle. Some could go even higher.
But if you are the adventurous type and would be game enough to look for the best buys, then I can recommend you a few places to check out. If you are in Ortigas, you can go to Robinson's Galleria. There is a perfume shop there named "Perfume World" (Im not that sure) where you can get designer scents at a much lower price. I see occasional Creeds there and they are also much cheaper.
If you are in Makati, go to Glorietta and check out the basement shops (near North Park restaurant). There are two shops there that sells a variety of scents and even hard to find ones.
I also have other places that i can recommend you but i think you should start from there first. They are very accesible and not hard to find.
Good luck on your scent hunting!