The wheel you are interested in is not one that you would typically see on an M3. There are a number of wheel vendors/site sponsors here that understand wheel and tire fitments for your car and offer quality wheels at different price points. You can find lots of pictures of wheels mounted to cars in the M3 Photos/Video/Media Gallery
and the Wheels + Tires Sponsored by The Tire Rack
forums. Our wheel vendors advertise their offerings in the wheels/tires/spacers
section of the SPONSORS Classifieds/Groupbuys/Specials Area
. You can find out if forum members have had issues or particularly good experiences with specific vendors in the Vendor Comments/Review/Feedback Forum
While there is an E46 M3 specific forum here, the M3Post site and information is primarily focused on the current model E9X M3's. You might find more pictures of available wheels on E46 M3's like yours on a forum such as M3forum.net that has more of an E46 M3 focus.
To be sure you get a wheel that will meet your needs, it's important to know about wheel manufacturing methods and wheel performance standards. There is information about manufacturing methods here: http://www.m3post.com/forums/showthread.php?t=357430
and wheel performance standards here: http://www.m3post.com/forums/showthread.php?t=353224