not sure about canada... but in the usa... (100cad=92usd)
i've seen the ath-m50 for as low as $100 new but open box on ebay. normally $120
i've seen the ad-700x for as low as $115 new on amazon, normally about $140-150
i've seen the hd-558 for about $120
the sound quality once you get into the $100-200 range is really good for the money spent.
if you want cheaper...
the pioneer se-a1000 is $60 and was recommended as an overlooked jewel in that pricerange
the ath-t500 is $68 and also gets good reviews for the price range.
quality isnt going to be as good as the ones i recommended which are available for the $100-120usd range though but its your choice if you want to spend that much or not.
some other possible choices..
http/www.head-fi.org/t/656055/best-choice-for-headphones-under-100