I did a full replace-job on my black e46 - wheel caps, front, rear and s.wheel.
DIY from e46 zone here:
http://www.e46zone.com/forum/index.php?showtopic=13421&st=0
As my Z is midnight blue, the black clashes, so I've only put the wheel caps on and sold the other badges.
They may not be genuine BMW, but the quality of the ones I bought from the US (on eBay) were as close to OEM as you could get...
Si