Based on what I've read, canadians pay about 11.5% of GDP now. about $6600 per person. It is lower than in the US but growing, even as a portion of GDP.
I wish Americans all the best in solving their healthcare issues, but I don't think you will be able to reduce costs by switching to single payer. I don't think anyone has been able to reduce costs; freeze growth, but not reduce.
Again, I am just trying to be realistic. True single payer would probably be better than the current American system, so I think we can agree on that.