A friend of mine did this for a living in his early 30's, he said those flights are probably the most dangerous things he's done in his life. He'd fly commercial to Canada, scout around for a good plane, arrange the sale and the various bits and pieces of paperwork, strip it down as much as possible, install extra fuel tanks and some other gear, then go to Halifax, check the plane over once more and then start puddle jumping hop by hop until reaching continental Europe. You could not pay me enough to try a stunt like that, let alone several times.
If he was flying Halifax-Newfoundland-Greenland-Europe the planes must not have been too small, because the Newfoundland to the next hop distance is quite large. The absolute shortest single leg distances involve going through Iqaluit and then Greenland.
Interesting, I don't know what planes he was ferrying, and we lost contact years ago (I moved to Canada myself, he moved somewhere else in NL) so I can't ask. Possibly he did what you suggested, it would make good sense. Quite possibly Halifax was mentioned as the last stop before the end of civilization in terms of repairs and spare part availability, but I'm very sure he came through there.
It is an interesting thing though, the same planes that go fairly cheap in Canada are worth a fortune here in Europe so there definitely is money to be made.