How to minimize customs handling fees while buying online

Last year i bought some item online, its price was CAD$22 i needed this item very urgent so i selected DHL for shipping (I have same experience with other shipping companies) so total cost including shipping was CAD$100

Canadian customs imposed import duty considering item price $100, total import duty was about $10 in addition to that DHL charged me CAD$22 for agent/handing fee while paying customs so total cost of that $22 value item went to about CAD $130, in some other example i also paid $22 for paying duty $5

Please note that i do not remember exact numbers but here i want to discuss the situation based on real example.

My questions is,
How can i avoid agent fee while evaluating customs duty
Does shipping cost includes to the value of item when evaluating for customs? (often seller include shipping cost in the invoice and print total amount paid, but some time there is a separate invoice for shipping paid)

Note: for sure; here I’m not looking for any illegal solution, I live in a small city where i can’t buy items(tools) for my work locally and i have to pay additional amount each time i buy online.