B&H Photo Video offers the Sennheiser HD 700 Over-Ear Headphones for $505.37 with free shipping. (Amazon offers it for the same.) That's $45 below our April mention and the lowest total price we've seen this year. (It's a current low by $25.) They feature open-back ear cups, a detachable silver-plated oxygen-free copper cable, and 10Hz to 42kHz frequency response.