Does anybody know where I can find a black S4 Bumper or does anybody know a website which sells replacement S4 bumpers?

 

try the classifieds. other than that besides a junk yard the dealer is the only place to get one and you are going to get ripped off. no company makes one. if they did though they would be rich

 

yeah, body shops can get them to (from dealerships, junk yards, ect..) so you can try to see if they can help you get a descent deal. otherwise, bend over

 

Try this site: http://www.shokan.com

They specialize in parting out Audis; and usually have some S4's available. Although the front bumpers seem to go pretty quick - I'd say drop them a line and ask if they can call get hold of you as soon as they have one available.