Not that you should have to pay for it, but there's an electronics company in Michigan that refurbs the auto-dim mirrors, Sybesma's Electronics. Do a search; I think it's less than $100. They supposedly put a better kind of "electrochromatic" goo in it. As OrientBlau mentioned, if the stock stuff leaks on your console, it will eat holes in it - like "Alien" blood.
I didn't care for the tinting of the auto-dim mirror, so I replaced mine with a manual unit off eBay. I don't mind having to occasionally twist the ol' clown nose at night. No worries about destroyed consoles, either.
2001 325iT 5-Speed