[buymycards]

3 PSA graded cards weigh about 4.2 ounces. If you can keep the total package weight under 8 ounces, you can mail it, with tracking for $14.25. Between 8 ounces and 32 ounces is $21.25. This includes tracking but no insurance.

It will be cheaper if this is an eBay sale and you print the postage through eBay. They generally give you a nice discount over the prices that I quoted.

eBay also has a new Standard Shipping program for Canada which gives steep discounts. I have only used it once, and it worked fine, but I am not knowledgeable enough about the program to give advice on it.