Adorama via eBay offers the Sennheiser CX 475 Premium In-Ear Noise Blocking Headphones in Black, model no. CX475, for $16.99 with free shipping. That's $3 under our March mention and the lowest total price we've seen. (It's a current low by $13.) They feature a 19Hz to 25kHz frequency response, 120 dB sensitivity, and 3.5mm jack.