Allreli via Amazon offers the Allreli C6 Waterproof Wireless Bluetooth Speaker
in Army Green or Gray, model no. ALLMB0214, for $21.99. Coupon code "GQMUC6T6" cuts it to $15.39
. Plus, Prime members bag free shipping
. (Non-members can spend $35 or more to bag free shipping; otherwise, shipping adds $5.46.) That's $45 off list and the lowest total price we could find, outside of the mention below. This 4.5-watt speaker features a silicone casing, suction cup, metal hook, and auto shutoff.
A close price: Elivebuy via eBay
offers it for $16.42 with free shipping.