Try digging thrugh the various eBay sites, not all listings appear on the US site.
Sometimes you'll find someone that's obviously parting out a bike but hasn't listed everything yet or doesn't know that it has any value. If you see someone starting to do this use the "Ask Seller a Question" link and, well, ask them. A lot of motorcycle salvage yards have connections as well, expensive but if it's that one piece you need .....
I got some floating around somewhere if you want them, I took them off mine and filled the holes, just need to hunt for them. PM me and we can go from there.