I might sound like a dick but I'd weigh it, take dimensions and ask the buyer to sort out the courier themselves. I've wasted loads of time running quotes just for people to tell me "that's too much, can you not do it cheaper?" If anyone wants something big/heavy sent abroad now I ask them to sort out a courier themselves, if they really want it they'll do it, if not at least they're not wasting my time. Had this with a gearbox recently, £100 was apparently too much to send a gearbox on a pallet across half of the continent.....