There's plenty of Finnish sellers at etsy and as etsy deals with the payment it shouldn't be any issue. Language barrier is pretty nonexistent as well since almost everyone here understands english anyways. Shipping inside EU doesn't cause any toll/tax issues, so that's an option as well.
So, I don't see any problems with anything as long as you can get the payment trough either with credit card or via paypal/etc. Shipping from outside EU is another matter, that may come with added taxes/toll payments before the shipment is released. And then there's some limitations on what you can actually send via post office, but those mainly include things like medicines and plants/food, so I don't think that'll cause any problems.