Not quite headphones, but have been discussed on the site and the brand is obviously popular around here. These are Audeze's Filter speakerphone/smart microphone that they posted on Indiegogo. I purchased these on a whim, but turns out I don't have a setup that utilizes them so looking to sell. I tried the device once, but it's basically new. Paid $250, asking $150.

https://www.audeze.com/products/filter

Cheers, and sorry if this strayed too far from the headphone theme.