Canadian vs. US book pricing has always been odd, and it's never been eBook specific.
When I managed a bookstore in Canada during the early 90's the price differential between the two countries was usually $1.00CAD. With the prevailing exchange rate, that put the Canadian price lower in absolute terms. By around 2000 that had changed, with the differential increasing even as the exchange rates approached parity.
Canadians kept buying books as prices went up, so prices kept going up.
