These EPS control arms can be bought @ < ****************************************.com > and <
www.design911.com > in England for ~90 UK pounds. I've used both Design 911 and EPS suspension parts with good results - made in (I think) Czechoslovakia.
Note that these control arms only fit the front suspension of the Boxster, not the rear.
EPS also manufacture the roller bearing IMS retrofit, the subject of another (heated) thread, but I better not mention that......