I agree with the above post;
I find that Duty is generally paid on items over $20... sometimes you get lucky & no duties on sums higher than that... most of the time you'll end up paying something.
USPS also charges a $5 customs brokerage fee... The couriers charge way more for that. Recently had a $65 customs brokerage fee from UPS!

What makes me crazy is having to pay HST ( $15% harmonized sales tax) on the customs brokerage fee part of the duty ( as well as the 12.5%duty)

I always attempt to get a seller to under-value the declared value if possible. I'm not saying write "gift" or anything, just put a reasonable amount for declaration.... ( & please not more then i paid for it!!!)
some sellers actually Inflate the cost because they want to insure it for a high dollar amount