I've gotten the extrait three different ways:
- That little coffret they came out with for a couple of years, with tiny doses of several different parfums. It might come out again. (Edited to add: It was a Christmas thing.)
- A decant from The Perfumed Court.
- Friends went to Paris and bought me a bottle there. My understanding is that the Paris-bought stuff is better, because they use a better alcohol that, because it's potable, they can't use for export to the US.
I remember someone saying that there's such thing as "shopping services" if you want the authentic French stuff, but I don't know any details.
If you fear eBaying because you'd have to judge the result from memory, you could get a tiny decant from The Perfumed Court (I consider them thoroughly trustworthy) and use it to judge what you eBay. But I fully understand the nervousness about eBay purchases.