What about
Apex?
Their
EC7 and
ARC8 wheels come in silver, hyperblack, and anthracite. Any of those, especially the hyperblack or anthracite, would meet your requirements. Oh, btw, just say "no" to chrome.
They're considerably lighter than stock too, so there's less unsprung weight (better performance/handling), and they come in various sizes and fitments that work well with the Z4M. Lastly they're not 400 or 500 per wheel, they run around 300 dollars/wheel
We're running a set of 8.5 x 18 ET38 and 9.5 x 18 ET22 ARC8s on one car, and 9 x 18 ET42 (with small spacer) and 9.5 x 18 ET22 EC7s on the other. Both look great! Apex has great customer service and they're very helpful (obviously I'm a satisfied customer).