Yes, I've bought cars in Canada and brought them into the states and also hauled stuff into Canada. Getting into the states is usually easier. Despite what many will say about how easy or hard it is, what it really boils down to is your attitude and whether the border agent you get that day had their morning coffee and doughnut and no one interrupted their brake.
I've gone thru where they've hardly looked at the VIN and sent me thru, and I've sat for 3 hours while they went over every inch and piece of paper until something more interesting came along. That was actually kinda funny now, but I was sure irritated at the time. It was an ATV (89 Hond TRX250R) that a bike shop that a friend of mine owned built. The owner sold it to another friend of mine who then sold it to a friend of mine in Canada and then I bought it from him and brought it back to the states. They were slow at the crossing and this was shiny so they spent extra time. Thing is, I had 2 previous titles, build sheet, bills of sale, Canadian import paperwork, US export paperwork, etc. from all the people who had owned it so it was very well documented. Then someone rolled in behind me that looked like they'd spent all weekend smoking weed and suddenly my deal wasn't interesting anymore.
Generally as long as you are polite and have the paperwork the US agents are pretty easy to deal with.
