$10.50 from ebay. takes about 2 weeks for shipping from hong kong. But it works great. Hasn't fell off my window or let go of my phone. Its very impressive considering I have a 146db stereo in my car.
It has a locking back that holds the arm in posittion you want. and allows the phone to slide open and close very easily. And has a camera hole. So you could video your driving skills.
http://cgi.ebay.com/HTC-Touch-PRO-2-...item5634f26e16