Aukey Direct via Amazon offers the Aukey FM Transmitter Radio Car Kit
, model no. BT-C4, for $15.99. Coupon code "YD8DVOQ9" drops it to $6.99
. Plus, Prime members bag free shipping
. (Non-members can spend $49 to bag free shipping; otherwise, it adds $5.99.) That's $7 under the lowest total price we could find for a similar model. It features a cigarette lighter power supply, 3.5mm jack, USB charger port, and digital station readout.