Last December 2023 I traveled alone from Toronto Canada to Dallas Texas to look at a truck I was interested in. I took a good amount of US currency ($11,000) to make a deposit if I wanted to purchase . I had a bank receipt to prove where the cash originated from, declared it at the border and answered a few standard questions and was on my way. The party that was selling was more nervous than I. I said let's meet at a police station of your choice, which we did. I also stated I don't have a gun as it's prohibited in Canada. They thought that was crazy and need to change things. Anyway maybe I'm naive, stupid, too trusting or lucky but I have done the same thing many times with no bad results. I've come home without purchasing anything more times than not. I also incountered a situation where the other party was nervous that the cash I had was counterfeit. This was on a day the bank was closed so they had to decide whether to accept or not. They did and all was good. I got a Harley and they got a bag of cash. So to answer the OP's question, what I would do is go in person with a deposit or the agreed amount, meet in a public place or police station and go from there.
Just my crazy suggestion, you may disagree.