Although I've never smuggled anything across the border between Canada and the U.S.A., I've benefited from "cross border price comparison" on a few big ticket items.
My modus operandi is to present an advertisement for the item I want and to point out that considering the exchange rate and the hour's drive to the border, my equivalent price would be "This amount." More often than not, the merchant confronted by the choice: "Match Price" or "No Sale" capitulates.
Another consideration. . .
Warranty can be challenging. Many service facilities will not repair items purchased in another country.
A big issue is availability. Where I live, quite a few popular and effective pesticides are banned. They're available in the U.S. as well as other provinces. Why risk the penalties of international smuggling when the same item can be purchased in Quebec?
My husband once joked that one could tell where people's friends and relatives live by the weeds (or none) on their lawns.
Availability works both ways. After high-efficiency toilets became mandatory in the U.S., Canadian building centres did a booming business selling conventional privies to shoppers driving North.
And it's curious how European luxury car dealers in Canada require customers to agree to NOT export their new toy for a couple of years.
But my biggest frustration is the obstacles in buying simple little things using the Internet. For example, I wanted a new hinge for a laptop. They sell for $2 to $3. Shipping to Canada was $15! (I found one already in Canada for $5!)
Cheers, PW.
P.S. For years, diamonds were cheaper in Canada. Sadly, I don't buy many diamonds.