I like the idea of it, but I am nowhere near enough of a notes head to give them very specific direction. I really enjoy sampling the work of perfumers, reading the reviews in here and other sites and finding a nice fit for myself. But there is indeed no small appeal to wearing something created just for you.
It would interesting to hear from someone who has tried this.
I would wonder how much they work with a person to make sure they don't go way off course and create something horrible.
I would think that depending on the city you live in there are likely some local boutique type businesses that dabble in this sort of thing. I may have seen one here in Los Angeles, but can't gel the memory.