Canadian or pinks - Bobwins, I disagree with two of your points, You are right that there is an extra cost for the "fees" of the brokers involved, but I have never paid a cost as high as the $218 you mention in your example on a $5000 purchase.
Your example of .02 in fees on a stock selling for 8.30 is reasonable, but for the .50 stock that markup will be much less, typically in the .001 or .002 range. Different brokers charge differently, of course, and I have occasionally come across one that charges too much, but most of my trades are very close to the currency translation times the Canadian bid-ask prices.
I also do not understand your point about the Canadian vs US dollar. When we buy the pinksheet, its value changes along with the dollar exchange rate. When the US dollar drops vs the Canadian dollar, the pinksheet price rises by the same amount as the exchange rate. I don't see how I am any less protected against the currency exchange rate with the pinksheet than with the Canadian stock itself.