Curiously, I was just asking about international shipping (Israel) myself. Here is the link:
http://www.etsy.com/teams/5002/etsy-success/discuss/10571794/page/1/I have never shipped internationally in connection with my Etsy shop.
I just came back from the post office, where I inquired about shipping a soft cover book to Israel, and this is what I found, after the agent weighed the book and a cardboard envelope in which I was going to ship the book (I found out they have no book rates for international shipping):
First-Class mail would be $19.45 Dollars and it would take from 5-10 days in transit (maybe a little longer). I would have to fill out 1 customs declaration form.
Express mail would be $38.00 Dollars and it would take 3-5 days in transit (perhaps 6 days) and I would have to fill out 2 custom declaration forms.
I understand you are inquiring about Finland, and I do not remember how much my book weighed, but perhaps you could access the post office internet size and get a better idea. The above is just some general information that I thought would be of interest.
Good luck!