At one time this was a very common quasi-scam on eBay. I say quasi-scam because the total was usually a reasonable price, but the seller was cheating eBay on fees. At that time, eBay charged fees on selling price but not on shipping costs.
Today, and for a couple of years, eBay has been charging fees on both selling price and shipping and the practice has almost stopped.
In fact today, you are more likely to see listings offering Free Shipping, which really means the cost of shipping is included in the asking price.
Which is cheapest?
A $5 item with $10 shipping?
A $10 item with $5 shipping?
A $15 item with Free Shipping?
In defence of the seller, having said rude things about her, products cannot legally be sent lettermail. She would have to use Parcel Post within Canada and LightPacket or Small Packet internationally.
None of these services include tracking or Delivery Confirmation.
I take it these are cards like those in Magic The Gathering? Twenty two cards in appropriate protective holders could easily be over the maximum 2 cm thick allowed for letter or light packet. So while $23 does sound high, it would not be $1.25 for shipping.
Tracked service like ExpressPost starts around $14 and goes up with destination and weight.