It's still possible to get costumes in Vancouver.
Bang-on/Cherry Bomb - 843 Granville
Tons of costumes for men and women. I saw a cute bumblebee costume for women, super heroes (yes Batman is there too, and you know that'll be a sure thing with the ladies.)
Camouflage - 888 Granville
Medieval costumes for ladies, to fatigues for men. Still a selection upstairs.
Dare to Wear - 1028 Granville
The more daring wenches can go here. More fetish oriented but some cutey ones too. Must be pretty daring as the outfits tend to be a higher quality but considerably less fabric.
Scarlet Shop & Indulgence - 460 Granville
As posted earlier... a limited selection of extremely high quality costumes. Just gorgeous. You'll be the bell of the ball. It's a nice store you could buy your jammies and naughties in without feeling self conscious.
Glinda the Good Witch Costume from the Wizard of Oz/Wicked. Love it. Pricier side at $49.99 but totally worth it when you see it. The material is lovely and it's well cut. You won't look like a drug store tart.