Streamlights and SureFires are something I won't buy on Amazon or Ebay - they've been counterfeiting them for years. There was a guy on YT who bought a TLR-1 HL, or so he thought, and had some problems with it. Sent it to Streamlight for repair only to find out it was a fake. He had a couple others, IIRC.
eBay won't do anything about counterfeiters.
Since they're based in China or elsewhere, even if they are "US sellers", its just too easy to wind up burned paying retail or damn near, for poor Airsoft quality junk.
For things they ship yes - but there are people who sell on amazon and fulfill themselves and its a lot easier for them to slip in the bootleg stuff. Millions of products on Amazon, they can't police every item unfortunately.