We can't tell you where to buy airsoft guns because you aren't age verified. Please read up on the age verification information available in the forums and then message an age verifier in the area. Here is a list of the age verifiers in the GTA:
http://airsoftcanada.com/showthread.php?t=173758
Once you get age verified, we can tell you everything you need to know
Oh, and you get access to the classifieds which means you get to buy really nice used guns for super low costs!