Ebay offers Motorola - Wireless Car Adapter for Android Auto for $69.99 (reg. $99.99) free shipping.

Product Description:
The power of your phone on your car screen. Android Auto is a simpler, safer way to use your phone in the car. The MA1 provides a wireless connection to Android Auto on your car display to make it even easier get all your favorite maps, media and messaging apps on your car display.