I knew someone would get around to it - a TUV approved Magnesium Hub/CF Rim wheel for the 911/Boxster.
http://www.autofarm.co.uk/parts/Carbon_fibre_wheels
A set of 4 will run you $9,821.04 + Duty + S/H
Then there's tires, figure another $1,200-$1,500
Plus Mounting and Balancing - $150
And, you don't want the OEM Wheel Bolts corroding the Magnesium, so opt for these SS ones for $250.46 + Duty + S/H -
http://www.autofarm.co.uk/parts/wheel_bolts
In total, maybe $14k - $15k complete... Bragging Rights - PRICELESS!