Here's the resource I use for checking on likely shipping prices:
http://pe.usps.com/cpim/ftp/manuals/dmm300/Notice123.pdfI ship first class international from the US, but I also won't ship anything larger than the smallest customs for will take, which means none of my larger cross stitches go out framed. I could see coaster sets going beyond that in weight, so I don't doubt it would be significantly more money to send those abroad.
But I would still offer your wares abroad. If people would like to pay the shipping, let them!