Paying taxes/duty on used goods purchased in Canada

Riffer makes a good point about preparing for the worst because it is like a roller coaster, once you go over the top, you are no longer in control.  Best case is probably that you pay brokerage only, which I get charged for even small purchases from Partsconnexion, unless they are shipped by postal service. Some years ago, I believe it was around a hundred bucks or so for a SF preamp.  The NAFTA comments are valid but I would add, from experience, they are picky about the documentation being on a specific form and executed by the manufacturer, otherwise it may do you no good that they were manufactured in Canada.  One scenairo I have no experience with is shipping by a commercial carrier (I.e., a trucking company), although I would expect similar issues.

IME, you will probably get a bill for brokerage about a week or so after delivery,. I have never seen the seller pay for this.