Just because its on craigslist doesn't mean it isn't quality. A lot of people will get a boa (or any other animal ) then decide they don't want it for whatever reason and on to craigslist it goes. Many of these animals originally came from quality breeders. I would learn as much as you can about the various morphs/types of boas and how to recognize them, then pick apart the ads. You might be really surprised at what you come across!