FWIW-I recently contacted a seller of 3458A ref boards asking how/where he was able to get them. He claims that he received many as NOS from a closed assembly plant-you folks would know better than I if that story holds water. He also says that many are purchased when folks upgrade to the 4ppm option. I would agree that any of the $99USD are likely fake. However, if its a real LTZ1000 and decent components, it could be worth the price. Has anyone ever bought one at that price and can confirm whether the ref IC is real?