A CanPass is about $25.00 or so. Maybe this is the way to go...

http://www.cbsa-asfc.gc.ca/travel/ca...ateboat-e.html

In addition to a canpass, you will also need proof of US birth or
citizenship which can be a passport or a certified copy of your birth
certificate. Shortly after 9/11, I was almost turned back at Sidney
because I did not have a passport.

Since then, whith a canpass, I have never been checked or boarded, but
they still maintain the option of doing so.

Steve