If your items are less than 2cm thick and 500 grams you can list on dotCOM using Flat Rate (or even Free*) shipping with no problems.
But if you are shipping parcels, rates vary not only with dimensions and weight, but also with distance.
Run a few of your packaged items through this :
https://www.canadapost.ca/cpotools/apps/far/business/findARate?execution=e1s1
I use 90210 as a default zipcode.
Bonus.
You get 50 Free Listings every month on dotCA
And another 50 Free Listings every month on dotCOM.
Not for a while because new sellers have some annoying restrictions on the number and value of their listings each month. But keep it in mind.
You already know about the Paypal Hold right?
*Don't Panic!
Free Shipping just means including the shipping cost in the asking price.
Which is cheaper?
A $10 item with $5 shipping?
A $15 item with Free Shipping?