Sunvalleytek via Amazon offers the RAVPower Universal 2-Port USB Car Charger
in Black or White, model no. RP-CC01, for $8.99. Coupon code "THAN9OV4" cuts the price to $3.99
. Plus, Prime members qualify for free shipping
. (Non-members can spend $35 to qualify for free shipping; otherwise, it adds $5.99.) That's the lowest total price we could find by $3. It's compatible with most USB-driven devices.