If you are using the United States Postal Service (regular mail) and not a UPS/Fed Ex, it depends on the weight of the box. You can use USPS Priority Mail International Flat Rate Boxes, and depending on the size of box you choose you pay a flat rate. (I assume this is Kingston, Jamaica)
A small Flat Rate box: 8 5/8%26quot; x 5 3/8%26quot; x 1 5/8%26quot;.
Maximum weight 4 pounds.
Pay at post office:
$13.45 shipping
Pay online:
$12.78 shipping
A medium Flat Rate box: 13 5/8%26quot; x 11 7/8%26quot; x 3 3/8%26quot; or 11%26quot; x 8 1/2%26quot; x 5 1/2%26quot;.
Maximum weight 20 pounds.
Pay at post office:
$43.45 shipped
Pay online:
$41.28 shipped
A large Flat Rate box: 12%26quot; x 12%26quot; x 5 1/2%26quot;.
Maximum weight 20 pounds.
Pay at post office:
$55.95 shipped
Pay online:
$53.15 shipped
They also have a two flat rate envelopes.
Priority Mail: (6-10 business days)
Maximum Value for Contents: $400.00
USPS Supplied Envelope: 9 1/2%26quot; x 12 1/2%26quot;.
Maximum weight 4 pounds.
Post office: $13.45 Pay online: $12.78
Express mail (3-5 business days)
9 1/2%26quot; x 12 1/2%26quot;
Post office: $28.95 Pay online: $26.63
If you choose not to do one of those, or want to calculate it, this is the website for International shipments
http://ircalc.usps.gov/