Just a note to say that NGK Iridium IX, are the less expensive ones , and have a shorter replacement interval as compared to NGK Laser Iridium which is typically an OE plug.
Add amazon to the list.
As I’ve said before, a very experienced counter guy (yeah he had a lovely daughter that I worked with) at the pro parts store told me once that for whatever reason, the AC spark plugs sold at discount stores did not seem to be the same quality as the ones used at dealers and pro shops. It was just an aside comment but I think he was on to something and now with Mexican and fake plugs, I would never buy them from Amazon or Ebay. The cost is not that much different and as you know the “look alikes” look alike.
Years ago my BIL ruined an engine with faulty plugs when they came apart. I think they were Motorcraft for his Ford. Don’t know where he bought them though but when you think about the damage that can be done if one comes apart, you have to ask yourself if it’s really worth saving $10 or $20 buying from someone you don’t know?