Riversong via Amazon offers its Riversong Wireless Bluetooth In-Ear Sport Headphones in Black or Gun Matt for $19.99. Coupon code "Z5LDZ98Y" drops that to $9.99. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $6.10.) That's $3 under our mention from two weeks ago, $30 off list, and the lowest total price we've seen. These sweatproof headphones feature an inline microphone and controls, Bluetooth 4.1, and up to 8 hours of playback. Deal ends April 14.