I've personally seen fakes on ebay of sparkplugs. I bought off Amazon and they look legit but be wary. Amazon cost was about $35 for 4 plugs. Ebay fakes were $15 for 4 plugs. Get the real deal for $53 but ensure you're getting the real deal.
Buy from rockauto, here's a coupon code I received last week. 129222958120312182
If you ship to a business address, shipping is cheaper too.
I already purchased my qty 6 NGK iridium spark plugs from the Toyota dealer and I am prepared for the recommended 120K mi change. I also purchased qty 3 eBay Denso OEM ignition coils made in Japan (supposedly lifetime warranty) and plan to eventually install them on the back-side against the firewall.
My current reading is 98K mi and I will swap out the easy front three ignition coils next weekend. I will run the new coils to 120K and then move them to the rear firewall side during the spark plug change.
If a coil goes bad between now and 120K then it is RockAuto Denso coil at $53 a piece.
Lots of fakes on Ebay. I recently bought 8 Bosch coils on RockAuto and thought their price was too good to be true also, but they were legit. Had the hologram stickers on every box with a code to verify on the bosch website they were true parts.
Coils from ebay are a big mistake imo. The exception to this is if you're buying from a legit Dealership ebay store. I always call that dealership and make sure it's actually them running the ebay store.