Smartphone Sport Armband - iPhone 6 Plus/7 Plus/8 Plus/Galaxy & 5.5" Screen Phones - Various Colors (Free Prime Shipping) $3.9
RISEPRO via Amazon[amazon.com] has the Smartphone Sport Armband for iPhone 6+/7+/8+/Galaxy & 5.5" Screen Phones available in various colors on sale for $3.90 with coupon code D926BHT2.
Fakespot gives this product an A rating.
MULTIPLE SIZE OPTIONS – Adjustable Velcro Strap designed with 2 optional slots, enable you to adjust width from 9.5" to 14.2" (24.5~38.5CM). Fits perfectly with iPhone 6 plus/7 plus, Galaxy Note 2/3/5, works for 5.5" screen size phones with slim case on.