Fedex and UPS are cheaper and faster for shipping from california to Canada than USPS most times. But one important thing, shipping Fedex or UPS ground to Canada sucks for the person receiving the item as they both tack on an extra $25 fee for brokerage coming across the border. Use the expedited service (one up from the cheapest) which is usually $5-10 more but it saves the person receiving the item from $25 for clearance. The expedited service has free brokerage.
It sucked when canada post went on strike, I had important equipment that I needed stuck for an additional 5 weeks sitting at the local post office and I couldn't pick it up :/