Hi there,
Although I'm not participating in the exchange I may be able to help. If you mark the item as a gift the recipient will be exempt from customs fees if the value is under $60 Canadian. Be aware though that if customs inspects the package it needs to look like a gift. Enclosing a gift card helps. Otherwise commercial goods are duty free if under $20 Canadian.
This info is from Canada Post:
"Customs officers may open and inspect all incoming mail, except letters less than 30 g, without permission from either the sender or the addressee.
Gifts from friends and relatives, valued at $60CDN or less, are duty and tax exempt. Goods imported into Canada, valued at $20CDN or more, are subject to all duties and taxes."
I believe gifts from abroad into the US are duty free if under $100 US.