SoundPEATS Audio via Amazon offers the Soundpeats Bluetooth V4.1 Wireless Mini In-Ear Headset for $15.29. Coupon code "MRP9RUQT" cuts it to $11.01. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $6.03.) That's $4 off list and the lowest price we could find. It can connect with two smartphones or tablets at the same time and features talk time of up to three hours.

Update: The price has dropped to $14.79 before coupon, $10.79 after.