I generally shop in ebay, and never had problems regarding fake fragrances. Although you have to be careful with the more popular ones, you find more fakes of them on ebay. Armani, Chanel, Creed seems to be brands that you have to be careful if the price is too low.
For stores, i usually shop in fragrancenet, which has a large variety of products. You can also find discount coupons online, so you`ll have a lower shipping with them. My packages from there usually takes 20-30 days to be delivered and they aren`t taxed in general. Always keep an eye on fragrancenet, hard to find items just pop there with great prices.
I also use fragrancex, but you have to be warned that it`s not so safe here in Brazil. Their packages take in general 2 months to be delivered, and you may be taxed with more frequency than fragrancenet (at least it was my experience). But, you`ll always find huge discounts there, so it may be worth the waiting,
There`s also strawberrynet, which does nice promotions from times to times and it`s also one of the few which the shipping is trackable inside our country. Be warned that it's one of the most taxed stores on Brazil, but they also have a program of reedeming taxes.
I have also already ordered from feelunique, which is a store with less options than the mentioned above. But they are a british store, and british shipping is very reliable, so the chances of your package get lost are small. They have free shipping, as fragrancex, and you can also find coupon codes at internet.
I also recommend you reirien, which has hard to find fragrances, interesting samples and different shipping options available. I have shopped there using the first class shipping and didn`t have any problems. They also send you free samples with your order.
I have never tried perfumeemporium, but this seems to be another reliable store, with great prices and with coupon codes on the net.
Scented Monkey is not a good option for Brazil. They don`t ship to here using the USPS shipping, they use courier options, so you`ll be taxed no matter the value of your package. They also have a confuse costumer service, if you search on orkut you`ll find some complains about this store from individuals in Brazil that made orders there.