Lumsing Bluetooth Car Kit, $6 with code 534QGJ4K

We see deals on Bluetooth FM transmitters pretty often, but $6 is simply unheard of. All you do is plug the dongle into a USB car charger (or the included one), connect your phone over Bluetooth, and select an unused FM radio station. Sound quality will take a hit compared to other methods, but this is a great solution if you own an older car without a built-in AUX jack.