All you have to do is take apart any radar detector you have now and put it in your mirror (just scratch off the inside coating in a small square sized patch). (I actually plan on doing that with the compass mirror I installed this past week.)
If the radar components don't fit in the mirror, mount the detector somewhere unoticeable, and run the LED's inside the mirror. Man, I can make one for free! $1200.00 is OMG ridiculous.
But pretty cool, since I was thinking of the same thing.