What is the most expensive herb oil?

I'm curious to know, what herb oil holds the title of being the most expensive on the market? Is it a rare and exotic species that requires intricate cultivation methods, or perhaps it's a traditional oil with a long history of medicinal value that commands a premium price due to its scarcity or unique properties? What factors contribute to its high cost, and what sets it apart from other, more affordable herb oils? I'm eager to learn more about this intriguing topic.