UltraProof via Amazon offers Prime members the Tethys Movee Waterproof iPhone 6 Case for $12.99 with free shipping. (Non-members can spend over $35 for free shipping; otherwise, shipping adds $6.07.) That's the lowest total price we could find by $6. Note that this protective case does not feature access ports to the headphone and charging ports; it's also not compatible with the TouchID sensor.