I've been looking online myself for pet boutiques in toronto (moving there on the 4th) and I've found a few... if you can find something in a store then you can at least save yourself the shipping and customs fee!
Metro Hound -
http://www.metrohound.com/doggear.htm - 1003 Kingston Rd.
Downtown Fine Pets - 595 Bay st.
Petopia -
www.petopia.ca - 265 Bartley Drive
John Andrew Pet Spa and Boutique -
www.johnandrewforpets.com - 31 The Links Road (quite expensive though, but maybe worth checking out)
Bark and Fitz - 2570 Yonge St. (I loooove this place - I go to the one here in Mississauga all the time - they get new stuff in a lot - but again, kinda pricey)
Bobo Canada -
http://www.bobocanada.com/ - 777 Bay St. (Bay/College)
Chic Boutique - 128 Harbord St.
Places outside Ontario, but within Canada (again, no customs fees this way)
www.coconapoleon.com (Alberta)
www.poshpup.ca (BC)
I'm sure you know of a lot of these places (if not all of them) but I hope you find what you're looking for. It's true, winter coats for these guys are crazy expensive. I just ordered some coats for Ruthie from
www.purecountrypetboutique.com (I asked them to mark the package as a 'gift' so that hopefully I wont get stuck with customs fees, but we'll see how that goes). Their prices are really decent (shoes for 12.99, coats $19.99 or less). Maybe you can find what you're looking for there...