Of course , you could always buy Canadian. 
Seriously, the GSP is totally inappropriate for Canadian buyers.
As well as the point you make about CBSA's informal policy basically to ignore imports valued under $100 or so (the legal standard is $20 CDN or less. That's about $18USD), the dumb decision to enroll newbie sellers by default and to make it difficult for them to drop out either single items or entirely, means that the least equipped sellers are the ones getting the new sales.
Which they are totally unequipped to handle.
If you spot a Conservative candidate during the election campaign, you might try to encourage him to help bring the $20 shipped goods standard up to $200 to match the cross-border shopping standard.
The $20 has been in place since 1985.
Let's move into the 21st century.