How can I ship to Canada so Buyer pays no Duty?

I've heard how people are getting ripped off with brokerage fees from UPS. If I understand correctly, shipping via US Post Office will not incur fees? I am, however, reluctant to ship tubes this way. I'd probably never collect on a claim for broken or lost tubes.

I also wonder about the other way around, buying stuff from people in Canada. Someone told me you get slapped with a large duty, like 40% of the value of the item.

This is baloney and there must be a way around this.
Appreciate anyone's input.
Shipping USPS to Canada will incur a $5 admin fee but the end user will still pay taxes(fact of life) Insurance is a bad thing either UPS/FEDEX or USPS, sometimes it can take months.

Its know that one of the only ways is to ship to a company and mark "commercial sample",and no value in the custom declaration. I used this on cables I test and return.

My suggestion: Pack them well and these tubes usually come from Russia or other and survive the trip to US, if properly packed, should survive to Canada. The end user will end up paying taxs ...unfortunatly, such is life
The only way is to list value as less than $50 and declare as gift or mark as "commercial sample" with no value. Either way the item cannot be insured and must use good old U.S./Canada post.
All tubes I buy have been shipped this way with no problems.
Good luck
Note them as a gift.I believe this is one way to get around this.Maybe someone else can shed some light on the situation.
There is a NAFTA form that can be filled out to show no duties are due (because of NAFTA). I sold some Nordost SPM cables to a guy in Canada last year and shipped by Fedex. I cannot remember the form, it was provided to me by the buyer when he sent me the payment before I shipped. Without the form, he would have had to pay up. Maybe a call to US or Canadian customs will get you the information.
Stuff made in USA and Canada are duty free. Smaller stuff ship via mail to avoid duties and brokerage. Larger items, make sure you fill NAFTA form so that you can get duty exemption.

UPS is a ripoff artist as they charge too much brokerage.
As a frequent buyer/seller across our borders I can tell y'all that NO EXCISE DUTY is now charged, though Federal GST @ 7% (General Sales Tax) and PST (Provincial Sales Tax) - rate varies, though NONE in Alberta and those taxes are COMPOUNDED! And that is calculated on the converted currency (now $1 U.S. = $1.62 Can.).
It is true that gifts and items under $50 are not taxed at all. However, with FedEx if the item is valued over $1600 (Can.) a commercial declaration must be filled out. The bugbear is the "brokerage" fees...these are a total rip-off for doing NOTHING and truly dispensible if they wished, except, of course, for commercial shipments.
For large items drive over and bring it back...less risk factor all around...but do NOT LIE (too much) on the value at the border since these guys can check readily as to the true value and if they found you out they could confiscate the item as well as the VEHICLE carrying it...and you. Pay up at the border. Watch your paper trail. And you could mitigate the value by using the wholesale or disposable value...maybe? Don't forget your exemption.
Maybe I should move!