They started getting serious in the early 90s when crude went above $20. At that time Suncor's break-even point was $13. Your assessment is correct about the other companies, though, because until fairly recently Suncor was the only serious player in oilsands development.
I understand there are four players, Suncor, Shell and two others. I was not surprised when Koch pulled out after millions invested. They will buy from Suncor, Shell, etc. Its not their philosophy to be third or fourth in any market.