Like Kevin said, know the airline and their baggage restrictions. They're all a little different and they also seem to change frequently within each airline. I've only flown American Airlines for hunts and their current policy is $30 first bag, $40 second bag, both up to 50lbs. 51 - 70 lbs is $100 up charge and 71 - 100 lbs is $200 up charge. I fly for work quite a bit so my first 2 bags are free and I only have to pay the overweight fee. On my last hunt I didn't have time to freeze the meat before flying home, only enough time to chill it. I bought the largest, cheapest ice chest locally that fit the airlines baggage dimension limits, duct taped it shut and checked it. Worked great.