Right - I've done some investigation regarding sending the bass to Portugal, and it works out as follows: -
1. The bass must be packed in a hard case, otherwise insurance is invalid. Let's say £35 for a 2nd hand hard case.
2. The postage is in the region of £60 (based on 2 replies I've had from couriers so far)
So, we're already talking £95 on top of the price, plus there's still the danger it'll get damaged in transit.
A cheaper and safer alternative is that a number of budget airlines in the UK offer return flights from Portugal to Birmingham for £50. Hop on a plane, bring cash, I'll meet you at Birmingham airport with the bass, buy you a beer, we do the swap, and you fly home safe in the knowledge that you're looking after it, and not some hairy postal worker!
I'm about 30 mins from Birmingham airport, but will happily take a couple of hours off to meet up there, if that helps. It just seems a little expensive if we go the courier route.
Let me know,
Mark.