Hi Lynnie25,
We haven't yet gotten our ship-by-FedEx system in place (I think it's going to require Mr. FedEx stopping by again to install some new software for us, and also train us on how to use it).
But when I looked over their international rates, there isn't a cost advantage to using FedEx, for customers in really distant countries, such as Australia. Working from memory - because I don't have the rate chart in front of me - I think it would cost $3 - $4 more to ship that flat-rate envelope by FedEx rather than USPS. The only advantage is the tracking, and it might arrive a little sooner.
My guess would be that it's not worth $3 - $4 just to have package tracking. But it is a valid question to ask: what *is* tracking worth? Maybe $1 - $2?