I've been looking for rims and came accross this neat site. Just select "all wheels" link and chose your make and model. You can even chose the color of your Z and interchange wheels. This way you don't make the mistake of buying wheels that look nice but don't go with your car

http://www.discountpartcenter.com/

 

They just link to tire rack and keep their top frame.

www.tirerack.com is the place to go.

 

I've had good dealings with WheelMax.com