Traveling with a Chinchilla

If you have to fly with them, keep reading, there are options, however, it will stress them out, and chins that are stressed do not act predictably. There are horror stories of chins in stressful situations turning on their "mates" or "roommates" which would normally be completely unexpected. Also, in a soft-sided carrier, they can chew pieces of the carrier off and eat them, also a potential of creating an escape hole, let alone them getting sick on plastic in their system.
I bought a hard sided small size carrier that had lockable sides (necessary to travel with any pet on an airline), put in it his plastic fish bowl on its side with chin sand in it, it calms him when traveling to sit in the sand. I think he likes the small confined space with no sharp edges, therefore if he's bounced around, it doesn't hurt as much.
That being said, one carrier to travel with is cheaper than two (although cost it out because a carrier big enough to hold both small carriers will probably cost close to what it would cost to ship them both in separate smaller carriers). Definitely if their cages could be next to each other, it would reduce the added stress of being separated during travel.
Also, be aware of the temperatures when you're traveling, too cold, or too hot, not good. Travel in spring or fall when temperatures are more moderate in both the location you're leaving and the location you're going to.
LOCK THE CAGE WITH TIE STRAPS OR SOMETHING EQUALLY DIFFICULT TO REMOVE AND REPLACE WITHOUT NOTICE. Sometimes airport staff get curious and if they stick their fingers in and it seems friendly, they may try to take it out of the cage which could mean it gets lost. Also, if for some reason turbulence causes the cage to bounce, it won't open.
Afterwards, when you get home, have plenty of sand on hand so they can spin and clean themselves lots, they've probably peed on themselves during the flight and will need to be clean. My chin went through 3 pouches of sand, successively, cleaning out the fish bowl in between each, before he was looking like normal after the flight. But after that he seemed fine in about a week after.
Just think of us on the plane if we'd never seen or heard of a plane before, it bothers our ears, creates stomach upsets because of turbulence, it's scary and loud and the sensations are inconsistent throughout the flight, one minute up, one minute down, one minute side to side. It's got to have similar effects on the chins ears and body systems to some degree or other.
And I agree with Amanda, sometimes traveling with your pet chin is necessary and advising people simply not to do it, isn't very helpful. Overall, my chin has never been as skittish as the chins described on this site. Don't know why. He just seems to be more mellow than described here. Much more "socialized" to the human way of life. Maybe the founders of this site think that's wrong, I don't know. I do know I've found lots of useful information on this site and it educates people generally about chins. I recommend it to people, but I also tell them each animal is different and has it's own personality. You'll know if you're stressing your chin out too much.