Well Portugal is in the EEC, so you can forget the customs fees and taxes side of things if you buy within the EEC. You can buy from Mercanta by the bag at the same price as a UK roaster bar the shipping costs. They are a pukka wholesaler and importer. They don't supply home roasters - they supply the guys who supply homeroasters, eh Steve? I was lucky enough to visit them a couple of weeks ago and as I say I was very impressed with their attitude to sustainability, fair trade etc. That's not to say that all of their stuff is in this category, but it's up to you what you buy.
Sorry to keep banging on about Mercanta, there are other guys around (I can immediately think of alternatives in the UK, Germany and Italy) but I know you'll be pleased with the stuff they sell (especially the Brazilian Bourbon Fazenda Cachoeira, which is organic I think).
Anyway, whatever you go with, the best of luck to you, and please be sure to keep us informed of every step along the way.