I've been thinking about your concern about the mailing costs....I can definitely relate to that! I have all these grand plans of fancy ornaments to make and then I suddenly remember I not only have to make them, but I have to package them up, wrap them so they don't get broken or smashed, and then ship off the boxes. Yes, I see the $$$$$ stacking up.
So, this evening I had a "brain storm" (ouch!). I've been playing with a new Stampin' Up! die for my Sizzix Big Shot machine. It's a pretty snowflake that will make an excellent 3-D ornament. My BIG IDEA: cut out all the pieces, take a picture, write up simple finishing instructions and send the ornament in a flat envelop! Would that idea work for you? (Sending a 'some assembly required' ornament to others.)
By the way, I haven't signed up for this swap yet either. But, I'm in the US and would be happy to swap with you....I can handle a little assembling.