I am wary of american-based online shops though- ordered a few times from fragrancenet/ fragranceX but the goods never show. Had to wait painfully for 45days before paypal accept a claim despite I know customs probably confiscated it discovering its a perfume. As a result I never buy from american sellers unless 1) priority express mail 2) they are willing to bare the risk of customs.
I do recommend:
A) Strawberrynet.com - they NEVER fail to disappoint. Excellent packaging and stuff. [pm me if you want to borrow my customer loyalty discount]
B) Essenza Nobile - a german based shop with excellent prices on niche. They throw in 3 FREE 1.5ml samples of your own picking; just as long as they sell it and its in stock. I always go for ultraexpensive niche samples. They send by DHL post.
C) http://www.universalperfumesandcosmetics.com/ - a small family business in kuwait. Their website looks dodgy but don't be fooled. Excellent prices on niche too, and takes ~2weeks to get your order. They have a whatsapp line which you can chat with them if there is a problem with delivery.
PS: But going back to fakes... it really depends on the price point of that fragrance.... Issey Miyake is considered cheap when compared to giants like Frederic Malle. I doubt anyone will be bothered to produce a replica.