I don't know if USPS's international shipping choices reflect the domestic situation, but International Priority is just bizarre. For between $5 and $15 (usually) a packet can be shipped to Turkey International 1st Class. It will arrive in 7-10 days, 2 weeks if you;re really unlucky. International Priority costs $35 and up and will arrive in 2-3 weeks, a month if you're unlucky. The only advantage I can see with Priority is that it is fully tracked, so you can see how slowly the package is coming. Both services are signed for when they arrive (in Turkey, may be different in other countries).
Then for $3-4 more than Priority, a package can be sent International Express and will arrive in 5-7 days. I even had one package from ZPacks that arrived in less than 72 hours! And it's insured up to %100.
I'm not really sure what International Priority is for, yet it seems to be the default choice for many producers/retailers. I am currently awaiting a package sent from Ogden UT on 24 November. Arrived Salt Lake City, same day, left the next. Arrived Teterboro NJ on the 28th. Arrived Kearny NJ on 30th. Left Kearny NJ on 1st December. Arrived ISC NY on 3rd. No news since. This is one well travelled parcel. (Admittedly, the postage I paid was considerably less than the usual $35, don't know why.)
Not to knock USPS - the parcels arrive and 1st Class International is fastish and reasonably priced - but Priority is a strange beast.