Mailing to Finland is no different than mailing to Canada or any other civilized nation. Just put in the mail and the buyer pays the postage.
I see this comment is coming from Canada, so you obviously have not dealt with the US Post Office in a while.
Besides horrendously high prices from here to anywhere abroad, you also have to fiddle with paperwork to satisfy customs and other export bureaucracy.
I deal a lot in parts with Germany back and forth and sending from here to there is about twice the cost and double the effort than it is from there to here.
I don't blame anybody who does not want to deal with sending anything internationally.