Atlantic side of things. You can do mail order for JCrew and Target--they're online, after all.
I have relatives who are CA citizens who come across the border all the time (much more so since the exchange rate has been so favorable for them) and who run about like frantic contestants on Supermarket Sweep.
They go MAD for the jeans, for some reason, which they say are much more expensive "over the line," and the high-end basketball star sneakers, and Macy's (why I do not know, but they could spend days in there, more if they can get "coupons" from the flyers) but that's not all there is to it. Just about everything is cheaper on this side--clothes, food, gee-gaws, you name it.
I was at a CANADIAN TIRE (not a tire shop, for those reading along--it's just named that; they sell all kinds of crap, more like an Ace Hardware) which is in a mall in Woodstock, NB, just a month ago, and couldn't believe the prices. And that's pretending it's a dollar-for-dollar exchange, ignoring the strong Canadian currency factored in (making it even worse). No bargains to be had, except for some slightly shopworn packets of discontinued "Melitta" style coffee filters in the sale bin, which were going for a buck a pack. I bought a few of those.
I'd rather duck back over the US border before buying anything outta Canada. Not until the rate improves, certainly. I hope that Canadians keep coming over the border, though, and buying out the joint--it's good for our economy.
Edit, to provide an example:
Weber E310 three burner gas bbq grill:
Canadian Tire price: 749 CANADIAN.
http://canada.shoplocal.com/storeinsertlarge.aspx?storeid=2565897&rapid=693773&page=4&storename=canadian-tireWALMART (USA) price: 519 US.
http://www.walmart.com/catalog/product.do?product_id=10878990Big diff!