Deep in my heart I feel we should be a supportive brotherhood in this hobby. However with the big numbers $ that float around it's inevitable that the unscrupulous will weasel their way in.
That's why I trust no one unless they have a positive reputation on a site like this or they're an established business. Even the latter can be a crap shoot.
Always demand to see photos of the part(s) in a today context. Something in the background to prove it's not a photo from the 90's of a part he sold back then. Also never accept that it must be paid as friends and family and get a shipping quote. Most scammers don't want to be bothered doing that. Be weary of "free shipping" especially on something that will cost $75 or more to ship. I know that I would never eat that much $ just to make a sale.