Buying from unknown individuals or Amazon or eBay; maybe, maybe not. A dealer that's a member here, is a double bonus, such as Mike.
Please do not dismiss eBay as a source of legitimate specimens. There are many dealers there with a long and unblemished record of selling authentic meteorites. As with any listing on eBay, check the record of the seller. eBay does very little about fraudulent items in general, but if considering buying from a seller who sells only (at least mostly) meteorites, has been doing so for years, with nothing but positive feedback, you're pretty safe. When buying from anyone, anywhere, without a well regarded reputation, you need to educate yourself about the material in question. Know what the real thing looks like and how it should be priced. And yes, Mike is highly recommended.