International mail rates for FedEx vary depending on country, package weight and zone. Canada has two zones with the lowest rates ranging from $113-$170 dollars.
For most destinations outside the U.S., Canada, and Mexico, a letter weighing 4.3 ounces will need $5.45 in US postage for a "First-Class Mail International Large Envelope" rate. Priority Mail International, GXG, or Priority Mail Express International carry higher rates.
That will depend on where in the world you are sending it from, which you have not stated. Rates differ in each country and rates change all the time. Your local post office will give you rates at the current time.
It depends on the size and weight. You can check the rates on the USPS website.
Call your Local Post Office. They will refer to their International Mailing rates and give you the cost, the International Forms required for your mailing and the expected time of delivery. There are requirements and restrictions on mail pieces and contents. You can be sure of their professional services. They are there for YOU. :)
In 2010 the international rate from the US is 98 cents. Canada and Mexico are less.
You can go to USPS.com to check flat shipping rates. Priority mail is quite reasonable when shipping via ground
$1.05 for international 1st class; $16.95 for Priority Flate Rate International regular letter sixes
I assume you mean what airline has the best rates for international flights. If this is so then it is best to look for the national airline for the country you want to visit, assuming they have a national airline. They will be able to offer decent rates as they will be looking to make as much revenues as possible especially if it is outside of the US or Canada.
90 cents
First-Class Mail International Letter $1.05 (as of August 2012, but it increases every year or so).
Within the US, 44 cents for the first ounce. Each additional ounce is 17 cents. There are no zoned rates for first class mail.
Your answer depends on the service provider who supplies postal service to the location from which you want to send mail. Each research station employs a mail service provider who will dictate postal rates, that vary depending on the destination of the mail.