BuyDig offers the Able Planet Behind-the-Neck Sport Bluetooth Headphones, model no. BT400B, for $39.95. Coupon code "BTSET" drops it to $34.95. With free shipping, that's the lowest total price we could find by $24. They feature an on-ear volume control and microphone, folding headband, 30mm drivers, and battery life of up to 15 hours.