Secondipity via eBay offers the refurbished Sony Extra Bass Smartphone Headphones in Silver, model no. MDRXB950AP/H, for $24.99 with free shipping. That's $71 under the lowest total price we could find for a new unit. They feature a frequency response of 3Hz to 28kHz, in-line microphone and controls, and 47" cord.

A 90-day warranty applies, but it's unclear who backs it.