the definitive word on a banknote's value is, of course, the market. doesn't matter what anyone tells you, the note is worth what someone will pay you for it -- and that is REALLY good to remember (too many people get upset when they can't get "what the book said!" for their money).

the general guide to what things are worth (and mighty fine reading for money nerds like me!) is the publication Canadian Government Paper Money: A Charlton Standard Catalogue . it is published annually and mine is out of date (18th Edition 2006, R. J. Graham, Editor). it is available from Coin and Collectable dealers for about $15 (at least my checking reveals the 19th edition is...). the 20th edition is out around july.

another way of finding general prices is to see how much people are soaking others for banknotes on ebay. a lot of listings are there and a search of past auctions will often reveal what ludicrous amounts some people are willing to pay. :)

or you can ask here!... i can give you a ballpark figure that is a couple years out of date and at least one other reader of this forum (canucksfan, i believe) has the more recent edition and is pretty forthcoming with value lookups (despite his questionable taste in hockey allegiance :) ).