I wouldn't call a MB a higher level option. As for porsches, I think the higher level would end up causing you to shell out near $100k. So the real worry here is the new GT-R that is coming by Nissan, but those will be limited to 2000 units per year and will have a extreme mark up. So good luck getting one of those.
BMW is planning on the M3 being popular so I really doubt there will be any mark up for difficulty at all getting one.