I just had a set of 15mm hub centric spacers machined at a shop in Victoria, they did a beautiful job. I know a guy in Calgary with a machine shop that is exceptionally talented as well. PM me if you want a contact.
There are multiple places that can make custom spacers. Motorsports tech is one famous one, but there are many smaller places that make them as well. I have a friend that makes them for me for very cheap, usually about $150 for a set of 4.