Gunco on Colonnade road, Sports Action on St. Laurent (though my humble opinion is that their prices are out to lunch in many cases), and if you're willing to trek to Brockville, then Gun Mart is good.
Gunco for used guns, Sports Action for new if you don't want to drive 100km, and the odd used piece, and Gun Mart for a decent used selection AND better prices on new stuff. I'm not sure if Jason at Gunco really gets into special ordering new handguns, but his prices are generally quite reasonable on the used hardware.
FWIW, I looked at a 75th anniversary Browning Hi-Power in 9mm with adjustable sights and wood grips at Sports Action, it was in stock and I believe they were looking for $1100+tax, and about a month later when my father decided to buy one, he got it (same gun and options) at Gun Mart in Brockville for $879 or something. Only difference was he had to spend a Saturday morning and a few bucks in gas to drive out there to get it, and he had to special order it as they didn't stock that particular piece. I believe it took about a week to show up.
What are you looking for?
Adam