i know this isn't most folks idea of an alternative since the two cars are quite different but i'd seriously look at the Cayman S. In fact I'm seriously looking at it regardless of the M3 price. I won't make any decisions until i've driven the m3 though.
'05 X5/3.0 Sport (E53)
'03 540i/6 M-Sport (E39)
'91 325i/5 Sport Package (E30)
BMWCCA #360858 SCCA# 374179 NASA # 128290