$55,000 will get you the most expensive headphones in the world. They are called Sennheiser Orpheus and are not for your average Joe. It is claimed that they are not only the most expensive but also the best headphones ever created. There are only 6000 pairs.
Featuring a carrera marble base, that Sennheiser claims has certain acoustic properties to help eliminate “structure-borne noise” and an aluminum frame, the Orpheus was designed for sound quality with no concern for cost (obviously). ▶︎ Read article
Here's a list of other redicilously expensive headphones.

Abyss AB-1266 ($5,495)

Ultrasone Edition 5 ($4,999)

Stax SR-009 “Earspaker” ($4,450)

Shure KSE1500 electrostatic earphone system ($2,999)

Audeze LCD-3 ($1,945)

Grado PS1000 ($1,695)

Sennheiser HD800 ($1,500)

Beyerdynamic T1 ($1,399)

Hifiman HE 6 ($1,299)

Audio-Technica ATH-W5000 ($1,200)

OPPO PM-1 planar magnetics ($1,099)
