Here is where i got my poly bushings. They have quite a few nifty MKIII products. Good guys they are.
Champion Toyota
http://www.trdracing.com/supra/supra.html
Oh and poly bushings don't wear out faster. They ride harder and as such arn't quite as comfy (which is why i'm riding on Tokico Illumina IIs) but they handle better. Rubber is softer and so they don't make the wheel jerk quite as much when you hit bumps while turning or whatever because they give a little. The Poly bushings send it all right on through.