The problem is, just buying your own atomic clock won't make you know the exact time. Have you ever wondered why Coordinated Universal time is called Coordinated? Well, I don't know. It could either be because it's generated by multiple atomic clocks around the word that are synchronized together. Or it could be because it's syncronized by leap seconds to the cosmologic time defined by two trees of Valinor (the relevation of the Sun around the Earth since the reforms).