Hisagadget Inc. via Amazon offers the Esky CMOS License Plate Frame Rear Mount Camera, model no. EC170-09, for $31.99. Coupon code "77RI5U66" drops it to $24.99. Plus, Prime members bag free shipping. (Non-members can spend $35 to bag free shipping; otherwise, it adds $5.89.) That's the lowest total price we could find by $8. It features infrared vision, built in distance scale lines, and a 170-degree viewing angle.

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