When I first moved to this area back in December of 2013 there were numerous Canadians going back and forth over the border north of Eureka. They'd make trips to Costco in Kalispell and head home loaded up with all kinds of goods. I don't know whether they had to pay duty on those goods but it seemed like it was worth the effort. They most likely had property here and would combine a weekend getaway with a shopping spree.
I've crossed the border twice in my time here. Once to visit the town of Fernie and once for work to visit the Korth Group in Okotoks, Alberta. I'd drag a tractor implement or two over the border on a weekend getaway to help out an OTT member.