Many of the Ngaio Marsh books are available in Canada from Kobo ... but at net CAN$13.35 each. I'm not sure what HarperCollins is smoking with this marketing gambit.
On the other hand, many of the Ngaio Marsh books are availalbe in Canada from Amazon ... at net US$7.68 each ... and the Canadian dollar is currently worth MORE than the US dollar. Same ebooks, same HarperCollins ... 45% cheaper.
And, not to put too fine a point on it, the adventurous might find the entire series lurking under an e-rock with a little e-digging ....
Another note: H R F Keating's Inspector Ghote is set for re-release by Penguin in handsome new editions beginning in April. Hopefully there will be e-editions of those at some reasonable price. They, too, are set in India. A note about the release is here:
http://hrfkeating.com/news-discussion/