Used Audio Technica ATH-M40x for $82~

As of the time of writing, the Audio Technica ATH-M40x closed-back over-ear studio-headphones are currently available in “Used – Good” condition for $82.40 at Amazon Warehouse Deals.

The above if you want a low price. In terms of bang for the buck, there is a variety of new condition M40x bundles that go for $100 to $110 that include extra items like a Fiio E6 portable amp or a Creative Labs Blaster portable amp or a carrying case.