About 5k miles ago I installed these Vertex rebuilt rear lower control arms with poly bushings up front on my '02S and have been very pleased so far.
http://www.****************************************.com/ShowItem/128301%20Porsche%20Rebuilt%20Control%20Arm%20-%20Rear%20Track%20Arm.aspx
When the time comes (soon I'm afraid) I'll be replacing all the front suspension pieces with Vertex remans.
Not sure you're going to save much by fitting new poly bushings yourself - unless your time is worth $10/hr (mine's worth at least $12).