- If it's something I worry might be from a reseller, I'll search for the same item on AliExpress, Amazon, Google, and make sure I'm not finding it anywhere else, unless it is clearly from the same seller as the Etsy store. I recommend searching for the exact same keywords as in the Etsy listing.
But seriously. In addition to what has already been said, read the reviews, but also look to see if buyers have posted photos of the products.