Groupon offers the Sony Wireless Radio Frequency Headphones in Black, model no. MDR-RF985RK, for $69.99 with free shipping. That's the lowest total price we could find by $5. They feature wireless listening over a 900Mhz FM frequency, 40mm drivers, frequency response of 10Hz to 22KHz, and a wireless range of up to 150 feet.

Note that new customers can apply coupon code "WELCOME" to knock an additional $10 off.