In case you didnt know, you will not be aloud to ride your bike across the Ambassador bridge, or through the tunnel, at Detroit-Windsor. Also at Port Huron-Sarnia, no bikes aloud on the bridge. There is a ferry you can take above Lake St. Clair, from Marine City to Sombra.
I think to take a taxi across from U.S. to Canada, there is a $40 fee for crossing the border, plus fare, plus tolls, plus tip. Not sure what it is from Canada to the U.S..