Tom - depends on what we're bringing across the border, how long we've been gone, etc.
I live just north of Niagara Falls - if you go into any of the shopping malls near Niagara Falls or Buffalo all you see in the parking lots are Canadian license plates.
Generally if you go for the day, you can bring in a minimal amount without hassle, unless your bringing in booze or smokes - Canadian Customs or Border Patrol as their now called don't like that.
I stopped going for gas or day trips long time ago when our dollar went for a crap. I still remember back in the late '60s when our dollar was worth more than the US dollar, but these days it's not worth it for me and I can cross the border in 20 minutes.
Years ago, as part of law enforcement, I was in charge of a unit that specialized in customs offenses. We focused on big ticket items. Having said that, NAFTA did change a lot of things. For instance, there was a time when you could import a brand new vehicle or one that was declared "antique" (more than 15 years old) but would have to pay duties and taxes. As far as I know, you can import any aged vehicle now but still have to pay import duties and taxes.
Longer trips you can bring in a ton of stuff duty/tax free.
The alternative is to attempt to smuggle, but you don't want to get caught. When I was a member of the RCMP I seized two Ferraris (a 308 and a 512 Boxer) that a guy had "undervalued". He had them shipped, declared them for less than he paid. We had the vehicles under seizure for almost two years. When his case was over he had to pay a hefty sum in penalties. He ended up selling the 308 so he could afford the penalties and keep the Boxer. He was a high school teacher and had an affinity for cars - he also had a Delorean.