On doing a search, it turns out I’d asked the question about countries selling land a few years ago and had forgotten that I had. However, no one in that thread contributed the wiki-list that hibernicus did in this thread, so it was good I asked again.
Rupert’s Land was given as such a sale in that thread and we argued about it. I’m sure that’s why I mentioned it in my post. I may not have remembered the thread, but I remembered the arguement to some extent. Anyway, argue with the people in that thread who thought it was a sale of sovereignty.