TomTop offers the Rock H2 3.4-amp Dual USB Car Charger in Black or Silver for $9.89. Coupon code "PAV0033SCX" cuts that to $5.89. With free shipping, that's around a buck under the lowest price we could find for a similar charger elsewhere. It features an LED display and voltage monitor.

Note: The countdown timer on the product page does not reflect an actual expiration time and resets daily. This item ships from China, and may take up to four weeks to arrive.