I suspect they are out of their minds. Don't let them add any hidden charges to your bill, just pay the customs on your end when it arrives. I don't understand why anyone buys from this company and raves about them. Bad ju ju in my book.
The problem is that B&H isn't the problem - UPS and FedEx and all the other couriers that handle cross border shipments are the problem.
When it is B&H handling it, they charge a quite reasonable brokerage and handling charge, plus they or their agents calculate and remit the correct amount of duties and taxes that arise when one imports items into Canada.
In comparison, when UPS and FedEx are doing it, they calculate the duties and taxes the same, pay them for you and then charge you an unreasonable fee for the process. They either hold your package hostage until you pay or, even worse, send you a whopping bill later. If you don't pay that bill, you exclude yourself from future service
Some retailers will send items using USPS, but that means poor if any tracking (due to the hand off to Canada Post. As to whether we end up paying anything extra, you can never predict. Sometimes it just arrives in the mail, other times it arrives with a bill for duties, taxes and a reasonable if somewhat arbitrary Canada Post charge for the calculation and remittance of those taxes and duties.
Other times you get a notice in your mail that the parcel may be picked up upon payment of the aforementioned duties, taxes and Canada Post charge.
The UPS and FedEx charges are usually much higher than the Canada Post charges.
I expect that UPS and FedEx provide much better service to B&H than the USPS does, and that the nature of the USPS/Canada Post tracking resources for parcels to Canada is unsatisfactory - thus the refusal to use the USPS.