They are illegal to import now due to a commensurate mite they bring with them from Africa that has a fondness for plant crops as well (cotton for the most part). They have been banned for over a year....maybe more than two. As they become increasingly uncommon / rare in captivity, price goes up. Most anyone who can is buying groups to breed, as they will never be seen in the USA again once they are all gone.
It took federal agents a long time to discover that mite was what was killing cotton crops and where it came from, so the penalties for importing them are very steep. $1000 per offense and possible jail time ("offense" is defined by the field agent, it can mean per import or per animal as they see fit).