I completely agree with cabledonut's experience. I took a mountain bike from Gainesville, Florida to Santiago, Chile in a cardboard box. I used similar preparations and arrived without any problems. The box looked pretty bad at the end, but the bike was intact.

Check with the airline(s) involved in your trip. I remember that I paid almost US$50 from Gainesville to Miami (really annoying inflexible US Air people), but got Miami - Santiago for free. If you take just a small amount of luggage (without considering the bike), people tend to be nicer in the airport, and sometimes don't charge you for taking the bike.

The good thing about cardboard boxes is that you can dispose of it (recycle please) on arrival. Then, when you need to return to your country, go to a bicycle shop and get another box, either for free or a very small cost.