Ok so if you breed your fish and decide to sell them your going to need to learn how to bag and ship them properly.
Get the bags:
I prefer Kordon Breathing Bags.
Purge the fish:
Purging is the stage where you put the betta in a jar of clean water and don't feed them. This should las for two days.
Bag the fish:
Use water of the same temperature as the bettas jar water but DO NOT use jar water. Now net the betta and put him/her in the bag. Now grip the very top of your bag while you plug in your air pump, then slip the airline tubing into the bag and wait till it fills up (but make sure to grip the top tightly while it fills with air). Then slip out the airline tubing and start twisting the bag (sometimes my bettas are very dizzy after this step, lol). Once it's tight tie it with a rubber band. Then insert the bag with the fish upside down into another bag then tie that bag with a rubber band and filp it back so the bag holding the betta is right side up.
Ship the betta:
Use Express mail. Simple ;)