Cristiano Ronaldo is the world's best soccer player right now, but that amount is pretty damn high.
According to BBC Sports, Ronaldo has a buyout clause of 1 billion pounds (over $1.5 billion in US dollars) in his contract with Real Madrid.
Cristiano Ronaldo has a one billion pound release clause in his contract, according to his agent Jorge Mendes who told BBC Sports in an interview “His buyout clause one billion, so it is one billion. If, for any reason, the club decide to sell him tomorrow for 300 million, someone will pay. Ronaldo’s agent goes on to say that Ronaldo ” loves the Manchester United supporters because he was there six years but he will finish his career at Real Madrid, for sure."
It's very, very unlikely he ever leaves Real Madrid, but the thought of a club paying another over $1 billion for a player is crazy to think about it, and it would be a first for any athlete.