Let's start here:
https://www.canadapost-postescanada.ca/information/app/far/business/findARate?execution=e1s1
You can enter the dimensions and weight of your small shipment and get the counter rate from Canada Post.
The eBay label price is based on that.
Then you can go here:
https://www.canadapost-postescanada.ca/cpc/en/business/small-business.page?
And get a Solutions for Small Business number if you don't already have one.
This gives you some small discounts and also gives access to the Expedited Rates which don't appear on the first link.
Now let's talk about risk.
LetterMail rates start at 92 cents.
You can use LetterMail for domestic shipments that are under 500 grams* and two cm thick.
But those shipments cannot be tracked.
Do you need to track an item that sold for $1.25**?
Most people are honest making tracking unnecessary-- except for your own comfort.
Actually you can usually ship small items to the USA as LetterMail, it's just not exactly legal. Meh.
And a few other points.
Auctions are a dying part of eBay. It's branding on the part of the site, but terrible for the sellers.
EBay doesn't care.
EBay is your landlord, not your friend.
If you are going to use Auctions (and okay, Collectibles is a category where they can work) DO NOT start at an opening bid that will make you unhappy.
If a game is worth $25 in your mind (or from your research) start it at $25. Or $15. Or $30 and accept Offers.
Most buyers nowadays can't be bothered waiting seven days to learn they lost to a last second sniper.
And the cherry on top is that Auctions have more Unpaid Item Disputes than Fixed Price listings, which means you not only lose the sale, you also lose the underbidder who has moved on. (It seems to be about four times as many UIDs as FP).
* Use metric. Canada Post went metric in 1974. Anything else you use will be a guess
** And presumabley cost you less.
