I have a Samsung phone....the TQi app works great, but the Traxxas phone mount is sold out everywhere.

I found this Phone Mount at Amazon for $15 shipped. I got it today, and it works perfect! It is fully rotational in every direction and has an E-Z lever lock. It's designed to go on a handlebar, so all you have to do is pad the grip a little so it can hold the top of the TQi tx bar that sits on top....because the clamp is just a hair too wide.

Other than padding the handle-bar grip, it's a perfect fit.