If you want to be all 'JDM' about it, there's a company called Vans that puts out headlight/corner spray. The paint costs about $20 for a can that's no bigger than the Krylon stuff. I've seen the 'light smoke' sold here locally and was tempted to buy it,I'm just too cheap to pay that much for a small can of paint though. They also had some weird gray paint for the whole headlight, never saw it in person though.
