Was AU$19.92 + AU$1.35 here a few weeks back, seems like a decent price.
Tl;dr of features: It's an FM transmitter with Bluetooth input, FM output. Allows you to play music via Bluetooth in cars which don't natively support Bluetooth. Also has 2x 2.4a charging ports.
Billed as AU$17.89 + AU$1.28 (AU$19.17) if AUD is selected. Otherwise US$13.92 (~AU$19.27 according to google) - Zapals conversion rates are (currently) really generous.