Every once in awhile, there's a posting in the Classifieds section on this forum for a grenade launcher. So get age-verified and check that out.
As for actual online retailers, there's a couple registered on this here forum and I've occasionally seen them with launchers in stock. As with the above, you'd have to get age-verified before you can get access to their wares.
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So yeah, short answer is to get age-verified. Since you live in Toronto, it shouldn't be more troubling to do than to find an appropriate person or location.
Here's a few instructions on how to get age-verified...
http://www.airsoftcanada.com/showthread.php?t=11474
...and here's a list of age verification representatives and their approximate areas of coverage...
http://www.airsoftcanada.com/showthread.php?t=74996
...as for any other questions you may have, feel free to post them. Just remember that no one will be able to help you purchase an airsoft weapon until you have been age-verified.