Sennheiser HD 600 Open Back Professional Headphone [Headphones] – Amazon Prime Members Only – YMMV $243.1

Amazon.com has the Sennheiser HD 600 Open Back Professional Headphone for $243.10 after coupon for prime members.
In order to get the discounted price, you will need an Amazon Prime account.
Above the description of the item, there is a line that says "Speak with an Amazon Harmony associate for discount codes and to learn more. Call me." Click on the link and input your phone number. An Amazon associate will call you and tell them that you saw the description about the discount and they will email you a code to the email associated with your prime account. Use that code to get the discounted price.
Edit: According to the person I contacted, the code is a unique 15% discount that will last a few days which will then transition into a 10% discount that will expire in a year.