My buddy and I have both bought these lights from that very eBay listing and are using them on our FiSTs as we speak. I can 100% confirm the are not OEM, they are aftermarket. That being said they are identical to the Ford OEM unit, and as you mentioned TYC does OEM copies. They are great quality and fit perfectly. I can take pictures for you if you want to compare them to the Ford OEM unit.
I have no doubts the Ford OEM unit is the bees knees but at the end of the day if it works it works. These work, so that is all I am saying. Not trying to stir the pot, you stock and sell a quality product without a doubt. I am just saying that for those looking to save some money, they can achieve the same results with the aftermarket unit.