Is it legal to sell Chinchillas in the United States?

They are legal in all states. Chinchillas are considered an agricultural product because they were originally primarily used for fur farming, so they don't fall under the "exotics" heading where you have to have permits or special set ups to have them. A while back there were one or two larger cities trying to ban them, I have absolutely no idea why, but it didn't go through. I'm sure more will try though, they always do.