Oh My, Thank you for the tip I too am in Oakville.
So far, I find bubble envelopes are the best. I use the Canada post shipping calculator from the Canada Post website when figuring shipping prices to the states. and then create Shipping Profiles on my store. I then use Etsy to print my shipping lables. I find Canada Post calculator and Etsy shipping calculator are the same., so that is good! Usually all my hair barrettes weigh very little so there seems to be a flat rate of about $5 for anywhere in the US. barrettes fall into the ' light packet' pricing. However, for some reason, the light packet feature from Canada post website not apply to items shipped within Canada! Its pretty dumb. So I went into my local hasty market and they said this 6x9 bubble envelope is only like $2.0 to ship anywhere in Canada.
Sorry, hope that helps.
When I print out the shipping label from Etsy, I simply tape it on the envelope and drop it outside in my mailbox. It's small enough to fit through the box slot!