I regularly drive to Odgenburg NY Post office about 45 minutes from me if I have alot of (bigger)parcels to ship.
It's incredibile the savings using the US post Office system. The savings more than pays for the gas getting there. (plus I fill up on cheaper USA gas while there.)
It's easy, I use UPS manifests that are free, scribbled out the UPS on them, lists my items I'm exporting, give it to the border guard, they stamped it, they never opened and inspected anything yet... and I'm usually back in Ottawa... total trip time 2 hours. Well worth the hassle of not using Canada Post "break and lose and overcharge system.