World Wide Stereo via eBay offers the 11.9-gram Klipsch Reference S4 Premium In-Ear Noise-Isolating Headphones, model no. 1013730, for $49.99 with free shipping. That's the lowest total price we could find by $18, although they were a buck less three weeks ago (since expired). Features include four different-sized ear tips, storage case, clothing clip, 10Hz to 19kHz frequency response, and more. Deal ends June 23, 2012 at 4:39 pm ET.