We integrated Taxamo (http://www.taxamo.com/) into Leanpub, and their posted fees (http://www.taxamo.com/pricing/) start at 20 Euro cents for every EU transaction. Non-EU transactions are free.

In terms of detecting whether the transaction is EU or not, there's a complicated workflow with 3 pieces of evidence etc, but (a) that's what Taxamo helps with and (b) if a bootstrapped Canadian startup can deal with this, presumably so could anyone else.