Super-Acc via eBay offers these Wireless Foldable Bluetooth Over-The-Ear Headphones in four colors for $13.99 with free shipping. (Chuanworld via eBay charges the same price.) Outside of other eBay sellers, that's the lowest total price we could find by $3. These closed-back headphones feature a wireless range of 33 feet, built-in microphone, and a frequency response of 110Hz to 20KHz.
Of note, expect this item to take up to four weeks to arrive.