Montreal shopping is a sport, but you can also enjoy it from home during the winter arctic freezes. A very interesting shop is St Laurent's BoutiqueUnicorn [at 5135 St. L.], which has everything and some neat jewelry, an even a cute tumblr as well. It always has great sales.
BoutiqueOlivia has an online shop, if you don't want to venture out [to Atwater's Place Alexis Nihon at 1500 Rue Atwater]. Boutique Camomille [here's their Instagram] is quintessential Italian high class elegance--with an evil eye 'blue eye' up by the top door frame as you leave, be sure to spot it! I always check in here to see what's new. It has tons of all types of demure, lovely outfits along with many accessories, so there's something for everyone, and it has gorgeous Serapian handbags [very Italian film star].
Au Kouign Amann [in the Plateau at 322 Ave. du Mont-Royal E] is worth flying to Montreal for, so be sure to stop in and get one of everything [esp. the famous almond croissant]--and a handmade fruit juice. They are literally like crack.