The Glass is easy to change on the standard mirrors the 2 auto dim wires positive and negative literally just snap onto the metal contacts on the mirror glass so its as easy as taking it apart, uncliping the wires from old glass, putting in new glass and snapping on the wires again and assembling the mirror. should take less than an hour.
M3 mirrors require soldering so its more time but still not bad.
i've had to do 3 different mirrors.
that guy Scott from Radar mirror has a good deal on mirror glass but hes not super enthusiastic about modding mirrors for the cool features he used to advertise.
when I asked him about getting an oval auto dimming glass from him that was the new 2 way glass... he quotes $500 for the glass alone saying its super expensive.
when i asked about sending my mirror to him to mod it for the digital compass or homelink (since Ive seen him do it before) he gave me a short winded email on how hard it is and he doesnt want to do it anymore so i just bought a $100 auto dim glass from him. he never even emailed to say when it shipped tracking etc... merely it just arrived one day.
i think hes just tired of doing mirrors and burnt out, doesn't seem very enthused like he used to in his older forum posts on M3forum.
Id rather buy auto dim glass from
http://www.mirrorjohn.com/#
he has more parts and is friendlier and more responsive.