Hubert Channon is in Sherbrooke... very nearby... he is well known for bows. http://www.hubertchanon.com/archetier.html
There is Violins Etc on St Urbain that has all sorts of stuff hiding in drawers.. http://www.yellowpages.ca/bus/Quebec...c/2606011.html
There is Jules St. Michel http://www.luthiersaintmichel.com/
Wilder and Davis do great bass bow re-hairs... they may have bass bows in stock... http://www.wilderdavis.com/
Most of these places don't have their full catalogue on-line, they are 'bricks&mortar walk-in operations'.
Best is to wait, until you are in town, and then go to all the stores one-by-one and try out all the suitable bows each has in stock.
Of course there are also bows in the used market, as advertised on kijiji, craigslist, and on posters in hallways at the universities.