Riversong via Amazon offers its Riversong Wireless Bluetooth In-Ear Sport Headphones in Black or Gun Matt for $19.99. Coupon code "4E9QKO3K" drops that to $12.99. Plus, Prime members bag free shipping. That's $27 off list, and the lowest price we could find, although we saw them for $3 less in March. These sweatproof headphones feature an inline microphone and controls, Bluetooth 4.1, and up to 8 hours of playback.