The 2004 model had the auto-dim mirror. I bought 3 of them from www.car-guts.com last year for $25 a shot, but now I see that that yard has gone to $75.
( used one, sold one, and gave one to maxcichon )

Car-Part.com--Used Auto Parts Market - look for 2004 model ONLY interior mirror : I see some there at $20

It is pretty easy to wire in the 12v from the garage door module, there is a thread on here somewhere about that, but it is a real bi**h to remove and install the new mirror itself.