I have the same problem, but I found some center caps in Motorsport. They were pretty cheap (6.95 a piece) but I dont know if they are the exact size. They also had the insert type if you're not looking for the screw on type.
> does anyone have or knwo where i can get
> some z center caps for my rims (a perfect
> set of four) i have seen 2 other z's with
> them and wnat them very badly