I don't know about ones in Vancouver, but if you drive a couple hours south, MSI and Pental in Seattle both have Super White and Macabus.

Thanks WindyCindyLindy. Anyone else have any advice?

Have you tried Margranite in Burnaby?

I spent much of the fall looking for quartzite in Vancouver, so I'm happy to share what I found. Haven't been looking since early November, so things may have changed. The bad news...I didn't see any Macaubas.
Alpha Stone had Super White...but didn't call it that.
Bordignon has some kind of white...can't recall what...a bit of White Princess and a new shipment.
Margranite has a huge selection of quartzite...White Pearl and a few other whites.
Hari Stone has lots of quartzite.
We bought Madre Perola from Hari Stone...gorgeous, but not as white as it sounds like you want.
Other than these places, didn't see much quartzite anywhere.

Thanks so very much for the helpful information! It's great to hear about one's own experiences. I really appreciate it!

saw a few slabs of Super White at Alpha, they classify it as granite.