The complete mirror is 3 parts- the cap which comes primed for paint, the glass, and the rest of it- which includes all the motors and electrics. The whole thing is around £150 IIRC. I removed the whole panel to replace the mirror, but it might be possible without, if a bit fiddly. It's held by one nut inside the door. The glass just levers out gently, it's very easy. The cap is a bit of a game to remove and refit without breaking clips, but it'll survive if you're gentle, you can prise some of the clips once the glass is out. The first time I did it it took all afternoon, but once you've done it once it's easy- took less than an hour. A lot of it is knowing how it all fits.