Lots of discussion here
http://f87.bimmerpost.com/forums/sho....php?t=1356500
http://f87.bimmerpost.com/forums/sho....php?t=1364877
M2 CS will likely be at or slightly more expensive than a base M3. Just logical. It will be more expensive than the RS3.
If you're comparing motor figures I can see why you would think that because as it stands right now at least in Canada, the RS3 is just slightly cheaper than an M2. But who cares? 400hp? It's FWD AWD for crying out loud. The motor is amazing but that haldex platform sucks bigtime. No manual option. So if either RWD or 6MT matter to you then we have a full stop.
Price wise though there is ZERO chance of the M2 CS being less or equally as expensive as an RS3.