I had the same issue locating titanium headset spacers. I ending up searching ebay and located a single source that had decent quality.
My suggestion would be to get a set of cheap 1" carbon spacers from Performance Bike and paint them. Forté Carbon Fiber Headset Spacer Kit
Aluminum spacers tend to be powder coated or anodized for color. Paint on aluminum would not hold up without some serious prep work.