I saw this video and I quickly see that what we saw on 3/31 is what Elon based on to say that most M3 will be around 42k.
www.youtube dot com/watch?v=Qr2FaDh-Hlg
I did a quick comparison based on what I saw visually with the current MS upgrade price.
Pano Roof - MS option = $1500, I expect M3 will be $1000 to $1250
The leather seats as seen is also $2500 option for MS, I bet for the M3 will be close to $2k
A larger battery for extended range is probably $8000 to $10k, just guessing if the standard battery is a 50Kw and we want a 70kw battery. MS is something like $13k between a 70D to a 90D
These are pretty much the features I'd like to have on my M3.