I've seen the work done by the guys at SD Tint in Sorrento Valley. They wrapped an entire Audi A3 in flat white that looked really good. If its just the roof, then I'm guessing it'll be no problem for them. Check them out and find out what they charge for it. It could save you a trip to LA.

FYI, SD Tint in Sorrento Valley did my tint on my IS350. After a week, some bubbles on my passenger front window did not go away, so they re-did it for free and with no hassle. Their service is pretty good in my opinion.