Amazon has the EnacFire Wireless Bluetooth Earbud (one piece, CF8002) for $22 - $7 off with coupon code 2ZGFRXFI in cart = $15 with free shipping on $25+ or with Prime.

Has built-in 50mAh Li-ion battery with up to six hours of music per charge, two wireless magnetic USB chargers, five sizes of eartips, and carrying case.