I used to sell on craigslist all the time. It really depends on what area you post in, and if you put it in general for sale, they can not flag you for selling your animals. There is no way to run an add permanently, you just have to keep posting, but it is free and worth the time if you get extras.
You can post in the pets section, but you probably will get flagged.
Breeding is prohibited, that's why you don't say that you are a breeder in your listing. Just say your just selling them as pets, and you don't mind if they turn into feeders.