Lots of scams out there and anything that sounds too good to be true is most likely a scam. My mom called me, said she was considering the purchase of an air fryer and found a website offering Ninja Foodies for 50% off, she asked me if it was legitimate. I looked up the site and there were complaints and the site had a poor trust rating.
For me, when purchasing primers or powder, I prefer to buy local, either through a gun shop or gun show retailer. For bullets and brass, either direct from the manufacturer or through a retailer that is well known and has a good reputation. Do I end up paying a little more? I'm sure I do, but I also get exactly what I ordered, not a substitute or worse, nothing at all.