eCase via Amazon offers the Kmashi Arma K3 Bluetooth 4.0 Wireless Noise-Cancelling Headphones in Yellow/Black for $24.99. Coupon code "ACJQZC36" cuts it to $15.79. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $6.07.) That's $24 off list and the lowest total price we could find. These sweat-proof headphones feature a 33-foot transmission distance, built-in controls, microphone, up to 5 hours of playtime and 150 hours of standby time with a single charge, and compatibility with most Bluetooth-enabled phones.