I remember reading a thread on here a few years back that listed weights for OEM and 18" wheels. As I remember, they were tremendously heavy...like double a good aftermarket wheel.
Their relatively heavy, but their cast wheels that went for less than a grand for two 18x10.5's and two 18x9's chrome plated. If you want light weight and good looks I recommend some chrome CCW Classics. Not really cheap though. The factory wheels feel pretty heavy to me.