Fine wine, white truffles, great truffle oil, olive oil, vinegar, all cheeses, prosciutto, a fine ounce of caviar.... we'd all probably agree on.
How about some more obscure items that you would/ would not pay for at a shop or restaurant? Kobe beef? Shark's fin soup -- can't appreciate its worth, so I wouldn't order it.
Find it odd that some will pay for something simply because it is rare. Most of the time, I would rather have simple, everyday ingredients of the very best, freshest quality. Are there other foods I'm unaware of that merit the price?