presenting: THE MOST EXPENSIVE HAMBURGER EVER.
... a fried quail egg ...
It costs $295. No word on how much extra if you want to add bacon.
Weirdly I've seen the fried quail egg on stupidly expensive foods before, but quail's eggs themselves aren't particularly expensive or rare. I bought a dozen for about $3 some years ago.
They taste a little different from chicken eggs, though I can't really explain how.