Amazon offers the Pyle 3.5" 200-watt 3-Way Weatherproof Mini Box Speaker System, model no. PLMR24B, for $19.99. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping adds $8.57.) That's the lowest total price we could find by $5. These waterproof speakers feature 70Hz to 21kHz frequency response, 4 ohms impedance, and a removable rustproof grill. A mounting kit and wires are included.
It's currently out of stock and is expected to ship by July 18.