try Air Liquide or Praxair. i am assuming you have an Air Liquide in a city as big as Ottawa. but be sure to check both places and any others people list. prices cary very drastically. for dry ice, Praxair charges almost $40 to fill my cooler, the guys at Air Liquide only ask for a ten spot...if that. same thing with LN2, Air Liquide wants $6/L while Praxair sells to me for $1/L or less. it all depends on how much they sell to larger customers and how much they have on hand.