Clicking in Automatic shift lever??

I have a 2007 Mountaineer, 6 cylinder. About 3 weeks ago, I started hearing a rather loud "click" in the automatic shift lever when I step on the brakes to remove lever from "park". I understand what the feature is for, but I was concerned that it would quit and leave me stranded in "park" so I visited the "dealer". The signal from the brake pedal is energizing a small solenoid which repositions a small plastic part. Dealer says:

1. Small plastic part is what is making noise
2. Part is not available separately; $407.00 for entire shifter assembly.
3. The new mountaineers also make this noise.

Any thoughts / solutions?

Thanks, Tom