eCase via Amazon offers the Kmashi Arma K1 Rugged Bluetooth 4.0 Wireless Speaker for $19.99. Coupon code "9FDV3IL8" drops it to $16.99. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $6.91.) That's $3 under our February mention, the best deal now by $20, and the lowest total price we've seen. This speaker also functions as a charger and features a waterproof design, 4,800mAh battery providing up to 35 hours of playback time, 3-mode LED flashlight, and Bluetooth 4.0 wireless range of up to 33 feet.