Walmart continues to offer the Stanley FatMax 140-watt Power Inverter, model no. PCI140, bundled with a Freestanding Keychain LED Light for $19.98. (Amazon has a similar item, but without the keychain light, for the same price.) Opt for in-store pickup to dodge the $5.97 shipping charge. That's tied with our mention from three weeks ago as the lowest price we've seen. (It's also the best deal we could find for just the power inverter by $6.) It plugs into your car's DC power outlet and features a 1-amp USB port, two AC outlets, 3-foot cable, and mounting kit.