Go through your results for flights to Cody/Yellowstone in the USA with Netflights. Although Delta Air Lines usually has the best prices, it's best to double check what's available for your travel dates.
If you don’t have set dates for when you want to fly to Cody/Yellowstone, try searching by month – that way, you can compare airfares throughout the year.
Look out for flights with Delta Air Lines, as they often have good deals. Or broaden your search by looking at other airports in the USA.
For even more options, check what other airports you could fly to Cody/Yellowstone from. You might be able to make a saving by going from a different airport or city.