Hey Shakey
I just tried Roof helmets in Google and came up with a company in mainland Europe that ship all over the world.
As I've never used them or done what you want to do, I don't know about their reliability.
Bear in mind also, we usually pay in £ what you guys pay in $ for most of our stuff.
EG:
A mountain bike in the US for $1500 could be, say, £1500 over here.
So, your $1500 is around £860
Our £1500 is around $2600!!
So if you see a lid for, say, £180, you're looking at around $300+ (+ shipping).
Also, if you can't get them in the States, you can't try one for size until it arrives!!
I'd never buy a lid unless it was from a store where I could try it for size.
I had a Caberg replaced under warranty and the new lid (obviously same size) didn't fit!
Also, I've tried the same size Shoei lid in different models and one fits, the other doesn't!
I love the roof lids but my melon is too big for 'em.
Good luck in your search.