It has nothing to do with the physical boxes... I give up.
EDIT: No I don't. Go to the USPS postage calculator and see for yourself. See what the cost is for identical type and weight between something domestic and something to Canada. The cheapest way to send a 1lb package via Priority is a small flatrate box (the box itself costs nothing - they send them to you free) whether it be to a US address or Canada.
Canada ~$13
US ~$5
Just trying to help your sell;)
8 oz is 4$ 4.05 to be exact
http://ircalc.usps.com/Default.aspx?country=10054&m=6&p=0&o=8
pick country
go to choose shape > hit the package selection > weight > continue to page 2
on the second page ignore the obvious expensive choices ....they hide the tiny first class selection.....
it's second one in the list in blue
| First-Class Mail® International Options |
+ 1
i prompted U.S. dealers to this page too (with similar instructions) who were willing to ship a small tube of Superlube grease but only at horrendous USPS shipping costs. In the end they didnt adopt my suggestion and i had to break the deal.